cleanup

62 files changed, 502 insertions, 497 deletions

diff --git a/src/interp/astr.boot b/src/interp/astr.boot
index 466185bb..abbac83c 100644
--- a/src/interp/astr.boot
+++ b/src/interp/astr.boot
@@ -45,18 +45,18 @@ module astr where
  
 -- Pick off the tag
 ncTag x ==
-   atom x => ncBug('S2CB0031,[])
+   x isnt [.,:.] => ncBug('S2CB0031,[])
    x := first x
    ident? x => x
-   atom x => ncBug('S2CB0031,[])
+   x isnt [.,:.] => ncBug('S2CB0031,[])
    first x
  
 -- Pick off the property list
 ncAlist x ==
-   atom x => ncBug('S2CB0031,[])
+   x isnt [.,:.] => ncBug('S2CB0031,[])
    x := first x
    ident? x => nil
-   atom x => ncBug('S2CB0031,[])
+   x isnt [.,:.] => ncBug('S2CB0031,[])
    rest x
 
  --- Get the entry for key k on x's association list
diff --git a/src/interp/br-con.boot b/src/interp/br-con.boot
index 29ad20c5..b11c18f4 100644
--- a/src/interp/br-con.boot
+++ b/src/interp/br-con.boot
@@ -44,7 +44,7 @@ namespace BOOT
 --conPage(a,:b) ==
 --  --The next 4 lines allow e.g. MATRIX INT  ==> Matrix Integer (see kPage)
 --  $conArgstrings: local :=
---    atom a => b
+--    a isnt [.,:.] => b
 --    a := conform2OutputForm a
 --    [mathform2HtString x for x in rest a]
 --  if cons? a then a := first a
@@ -60,7 +60,7 @@ namespace BOOT
 conPage(a,:b) ==
   --The next 4 lines allow e.g. MATRIX INT  ==> Matrix Integer (see kPage)
   form :=
-    atom a => [a,:b]
+    a isnt [.,:.] => [a,:b]
     a
   $conArgstrings: local := [form2HtString x for x in KDR a]
   if cons? a then a := first a
@@ -95,7 +95,7 @@ conPageConEntry entry ==
 --=======================================================================
 conform2String u ==
   x := form2String u
-  atom x => STRINGIMAGE x
+  x isnt [.,:.] => STRINGIMAGE x
   strconc/[STRINGIMAGE y for y in x]
 
 kxPage(htPage,name) == downlink name
@@ -647,7 +647,7 @@ mkConform(kind,name,argString) ==
       sayBrightlyNT '"Won't parse: "
       pp form
       systemError '"Keywords in argument list?"
-    atom parse => [parse]
+    parse isnt [.,:.] => [parse]
     parse
   [makeSymbol name,:rest ncParseFromString strconc('"d",argString)]  --& case
 
@@ -825,7 +825,8 @@ dbGetDocTable(op,$sig,docTable,$which,aux) == main where
     or/[gn x for x in tableValue(docTable,op)]
   gn u ==  --u is [origin,entry1,...,:code]
     $conform := first u              --origin
-    if atom $conform then $conform := [$conform]
+    if $conform isnt [.,:.] then
+      $conform := [$conform]
     code     := LASTATOM u         --optional topic code
     comments := or/[p for entry in rest u | p := hn entry] or return nil
     [$conform,first comments,:code]
@@ -854,7 +855,7 @@ dbAddChainDomain conform ==
   dbSubConform(args,kFormatSlotDomain devaluate form)
 
 dbSubConform(args,u) ==
-  atom u =>
+  u isnt [.,:.] =>
     (n := position(u,$FormalMapVariableList)) >= 0 => args . n
     u
   u is ['local,y] => dbSubConform(args,y)
@@ -862,7 +863,7 @@ dbSubConform(args,u) ==
 
 dbAddChain conform ==
   u := dbAddChainDomain conform =>
-    atom u => nil
+    u isnt [.,:.] => nil
     [[u,:true],:dbAddChain u]
   nil
 
diff --git a/src/interp/br-data.boot b/src/interp/br-data.boot
index bd04dcf7..29c3d534 100644
--- a/src/interp/br-data.boot
+++ b/src/interp/br-data.boot
@@ -119,7 +119,8 @@ buildLibdbConEntry conname ==
     header := strconc($kind,symbolName conname)
     buildLibdbString [header,#argl,$exposed?,sigpart,argpart,abb,conComments]
 
-dbMkForm x == atom x and [x] or x
+dbMkForm x ==
+  x isnt [.,:.] and [x] or x
 
 buildLibdbString [x,:u] ==
   strconc(STRINGIMAGE x,strconc/[strconc('"`",STRINGIMAGE y) for y in u])
@@ -133,7 +134,7 @@ libConstructorSig [conname,:argl] ==
       or/[CONTAINED(x,y) for y in u for j in 1.. | j ~= i]
   sig := fn applySubst(pairList($FormalMapVariableList,argl),sig) where
     fn x ==
-      atom x => x
+      x isnt [.,:.] => x
       x is ['Join,a,:r] => ['Join,fn a,'etc]
       x is ['CATEGORY,:.] => 'etc
       [fn y for y in x]
@@ -452,7 +453,7 @@ getArgumentConstructors con == --called by mkDependentsHashTable
   fn argtypes where
     fn(u) == "union"/[gn x for x in u]
     gn(x) ==
-      atom x => nil
+      x isnt [.,:.] => nil
       x is ['Join,:r] => fn(r)
       x is ['CATEGORY,:.] => nil
       constructor? first x => [first x,:fn rest x]
@@ -541,7 +542,7 @@ explodeIfs x == main where  --called by getParents, getParentsForDomain
     [[a,:p]]
 
 folks u == --called by getParents and getParentsForDomain
-  atom u => nil
+  u isnt [.,:.] => nil
   u is [op,:v] and op in '(Join PROGN)
     or u is ['CATEGORY,a,:v] => "append"/[folks x for x in v]
   u is ['SIGNATURE,:.] => nil
diff --git a/src/interp/br-op1.boot b/src/interp/br-op1.boot
index dad326ca..39340f6a 100644
--- a/src/interp/br-op1.boot
+++ b/src/interp/br-op1.boot
@@ -136,7 +136,7 @@ dbShowOp1(htPage,opAlist,which,key) ==
     key
   [what,whats,fn] := LASSOC(branch,$OpViewTable)
   data := dbGatherData(htPage,opAlist,which,branch)
-  dataCount := +/[1 for x in data | (what is '"Name" and $exposedOnlyIfTrue => atom x; true)]
+  dataCount := +/[1 for x in data | (what is '"Name" and $exposedOnlyIfTrue => x isnt [.,:.]; true)]
   namedPart :=
     null rest opAlist =>
       ops := escapeSpecialChars STRINGIMAGE CAAR opAlist
@@ -235,7 +235,7 @@ conform2StringList(form,opFn,argFn,exception) ==
       pred =>
         string? x => [x]
         u := apply(argFn,[x])
-        atom u and [u] or u
+        u isnt [.,:.] and [u] or u
       typ := sublisFormal(args,atype)
       if x is ['QUOTE,a] then x := a
       u := mathform2HtString algCoerceInteractive(x,typ,'(OutputForm)) => [u]
@@ -371,14 +371,14 @@ dbGatherData(htPage,opAlist,which,key) ==
         y                                   --no, create new entry in DATA
       if key in '(origins conditions) then
         r := CDDR newEntry
-        if atom r then r := nil             --clear out possible 'ASCONST
+        if r isnt [.,:.] then r := nil      --clear out possible 'ASCONST
         newEntry.rest.rest :=               --store op/sigs under key if needed
           insert([dbMakeSignature(op,item),exposeFlag,:tail],r)
   if key in '(origins conditions) then
     for entry in data repeat   --sort list of entries (after the 2nd)
       tail := CDDR entry
       tail :=
-        atom tail => tail
+        tail isnt [.,:.] => tail
         listSort(function LEXLESSEQP,tail)
       entry.rest.rest := tail
   data := listSort(function LEXLESSEQP,data)
@@ -417,7 +417,7 @@ dbGatherDataImplementation(htPage,opAlist) ==
           alist := [[key,gn key,:entries],:alist]
       reverse! alist
     gn key ==
-      atom key => true
+      key isnt [.,:.] => true
       isExposedConstructor first key
 
 dbSelectData(htPage,opAlist,key) ==
@@ -504,7 +504,7 @@ dbShowOpItems(which,data,exposedOnly?) ==
   for i in 0.. for item in data repeat
     if firstTime then firstTime := false
     else htSaySaturn '"&"
-    if atom item then
+    if item isnt [.,:.] then
       op := item
       exposeFlag := true
     else
@@ -549,7 +549,7 @@ dbShowOpAllDomains(htPage,opAlist,which) ==
 
 simpOrDumb(new,old) ==
   new is 'etc => 'etc
-  atom new => old
+  new isnt [.,:.] => old
   'etc
 
 dbShowOpOrigins(htPage,opAlist,which,data) ==
@@ -907,19 +907,19 @@ mathform2HtString form == escapeString
   form is ['BRACKET,['AGGLST,:arg]] =>
     if arg is ['construct,:r] then arg := r
     arg :=
-      atom arg => [arg]
+      arg isnt [.,:.] => [arg]
       [y for x in arg | y := (x is ['QUOTE,a] => a; x)]
     tailPart := strconc/[strconc('",",STRINGIMAGE x) for x in rest arg]
     strconc('"[",STRINGIMAGE first arg,tailPart,'"]")
   form is ['BRACKET,['AGGLST,'QUOTE,arg]] =>
-    if atom arg then arg := [arg]
+    if arg isnt [.,:.] then arg := [arg]
     tailPart := strconc/[strconc('",",x) for x in rest arg]
     strconc('"[",first arg,tailPart,'"]")
-  atom form => form
+  form isnt [.,:.] => form
   strconc/fortexp0 form
 
 niladicHack form ==
-  atom form => form
+  form isnt [.,:.] => form
   form is [x] and GETL(x,"NILADIC") => x
   [niladicHack x for x in form]
 
@@ -979,7 +979,7 @@ evalDomainOpPred(dom,pred) == process(dom,pred) where
     pred is 'T => true
     systemError nil
   convertCatArg p ==
-    atom p or #p = 1 => MKQ p
+    p isnt [.,:.] or #p = 1 => MKQ p
     ['%list,MKQ first p,:[convertCatArg x for x in rest p]]
   evpred(dom,pred) ==
     k := POSN1(pred,$predicateList) => testBitVector(dom.3,k + 1)
diff --git a/src/interp/br-op2.boot b/src/interp/br-op2.boot
index e29f362f..1e5ff436 100644
--- a/src/interp/br-op2.boot
+++ b/src/interp/br-op2.boot
@@ -203,7 +203,7 @@ getSubstSigIfPossible sig ==
 
 fullSubstitute(x,y,z) ==  --substitutes deeply: x for y in list z
   z = y => x
-  atom z => z
+  z isnt [.,:.] => z
   [fullSubstitute(x,y,u) for u in z]
 
 getSubstCandidates sig ==
@@ -415,13 +415,13 @@ zeroOneConvert x ==
   x
 
 kFormatSlotDomain x == fn formatSlotDomain x where fn x ==
-  atom x => x
+  x isnt [.,:.] => x
   (op := first x) is '_$ => '_$
   op is 'local => second x
   op is ":" => [":",second x,fn third x]
   ident? op and isConstructorName op => [fn y for y in x]
   integer? op => op
-  op is 'QUOTE and atom second x => second x
+  op is 'QUOTE and second x isnt [.,:.] => second x
   x
 
 koCatOps(conform,domname) ==
@@ -582,7 +582,7 @@ modemap2SigConds conds ==
 
 hasPatternVar x ==
   ident? x and (x ~= "**") => isPatternVar x
-  atom x => false
+  x isnt [.,:.] => false
   or/[hasPatternVar y for y in x]
 
 getDcForm(dc, condlist) ==
diff --git a/src/interp/br-prof.boot b/src/interp/br-prof.boot
index c79b121e..5b8d9113 100644
--- a/src/interp/br-prof.boot
+++ b/src/interp/br-prof.boot
@@ -155,12 +155,12 @@ dbShowInfoList(dataItems,count,buttonForOp?) ==
     htSay '"{"
     if count < 16384 or not buttonForOp? then
       htSay [ops,'": "]
-      atom sig => bcConform sig
+      sig isnt [.,:.] => bcConform sig
       bcConform dbInfoSig sig
     else
       htMakePage [['bcLinks,[ops,'"",'dbInfoChooseSingle,count]]]
       htSay '": "
-      if atom sig then htSay sig else
+      if sig isnt [.,:.] then htSay sig else
         bcConform dbInfoSig sig
     htSay '"}"
     count := count + 1
@@ -245,7 +245,7 @@ hasNewInfoAlist conname ==
   (u := getInfoAlist conname) and hasNewInfoText u
 
 hasNewInfoText u ==
-  and/[atom op and "and"/[item is [sig,:alist] and
+  and/[op isnt [.,:.] and "and"/[item is [sig,:alist] and
     null sig or cons? sig and cons? alist for item in items] for [op,:items] in u]
 
 getInfoAlist conname ==
diff --git a/src/interp/br-saturn.boot b/src/interp/br-saturn.boot
index f0297eed..1719be7a 100644
--- a/src/interp/br-saturn.boot
+++ b/src/interp/br-saturn.boot
@@ -383,7 +383,7 @@ htMakePage1 itemList ==
     itemType := 'text
     items :=
       string? u => u
-      atom u => STRINGIMAGE u
+      u isnt [.,:.] => STRINGIMAGE u
       string? first u => u
       u is ['text, :s] => s
       itemType := first u
@@ -425,7 +425,7 @@ saturnTran x ==
 
 mkBold s ==
   secondPart :=
-    atom s => [s, '"}"]
+    s isnt [.,:.] => [s, '"}"]
     [:s, '"}"]
   ['"{\bf ", :secondPart]
 
@@ -441,8 +441,8 @@ getCallBackFn form ==
   strconc('"(|htDoneButton| '|", func, '"| ",htpName page(), '")")
 
 mkDocLink(code,s) ==
-  if atom code then code := [code]
-  if atom s    then s    := [s]
+  if code isnt [.,:.] then code := [code]
+  if s isnt [.,:.]    then s    := [s]
   ['"\lispLink[d]{\verb!", :code, '"!}{", :s, '"}"]
 
 saturnTranText x ==
@@ -994,9 +994,9 @@ dbGatherThenShow(htPage,opAlist,which,data,constructorIfTrue,word,fn) ==
       integer? thing => '"unexported"
       constructorIfTrue =>
         htSay word
-        atom thing => '" an unknown constructor"
+        thing isnt [.,:.] => '" an unknown constructor"
         '""
-      atom thing => '"unconditional"
+      thing isnt [.,:.] => '"unconditional"
       '""
     htSay '"}"
     if cons? thing then
@@ -1480,7 +1480,7 @@ htBlank(:options) ==
 
 unTab s ==
   string? s => unTab1 s
-  atom s => s
+  s isnt [.,:.] => s
   [unTab1 first s, :rest s]
 
 unTab1 s ==
@@ -1612,7 +1612,7 @@ bcConform1 form == main where
       bcPred pred
     hd form
   hd form ==
-    atom form =>
+    form isnt [.,:.] =>
       -- string literals, e.g. "failed", are constructor arguments
       -- too, until we fix that.
       string? form or not (ident? form and isConstructorName form) =>
diff --git a/src/interp/br-search.boot b/src/interp/br-search.boot
index 3622b118..aa1d3cbe 100644
--- a/src/interp/br-search.boot
+++ b/src/interp/br-search.boot
@@ -68,7 +68,7 @@ grepConstruct1(s,key) ==
 
 grepConstructDo(x, key) ==
   $orCount := 0
---atom x => grepFile(x, key,'i)
+--x isnt [.,:.] => grepFile(x, key,'i)
   $localLibdb =>
     oldLines := purgeNewConstructorLines(grepf(x,key,false),$newConstructorList)
     newLines := grepf(x,$localLibdb,false)
@@ -104,7 +104,7 @@ grepForAbbrev(s,key) ==
          match?(pattern,symbolName a) and not tableValue($defaultPackageNamesHT,x)
 
 applyGrep(x,filename) ==
-  atom x => grepFile(x,filename,'i)
+  x isnt [.,:.] => grepFile(x,filename,'i)
   $localLibdb =>
     a := purgeNewConstructorLines(grepf(x,filename,false),$newConstructorList)
     b := grepf(x,$localLibdb,false)
@@ -250,7 +250,7 @@ mkUpDownPattern s == recurse(s,0,#s) where
 
 mkGrepPattern(s,key) ==
   --called by grepConstruct1 and grepf
-  atom s => mkGrepPattern1(s,key)
+  s isnt [.,:.] => mkGrepPattern1(s,key)
   [first s,:[mkGrepPattern(x,key) for x in rest s]]
 
 mkGrepPattern1(x,:options) == --called by mkGrepPattern (and grepConstructName?)
@@ -344,7 +344,7 @@ aPage(a,:b) ==  --called by \spadatt{a}
   arg := IFCAR b or a
   s   := pmParseFromString STRINGIMAGE arg
   searchOn :=
-    atom s => s
+    s isnt [.,:.] => s
     IFCAR s
   $attributeArgs : local := IFCAR IFCDR s
   aSearch searchOn
@@ -355,7 +355,7 @@ spadType(x) ==  --called by \spadtype{x} from HyperDoc
   s := PNAME x
   form := ncParseFromString s or
             systemError ['"Argument: ",s,'" to spadType won't parse"]
-  if atom form then form := [form]
+  if form isnt [.,:.] then form := [form]
   op    := opOf form
   looksLikeDomainForm form => apply(function conPage,form)
   conPage(op)
@@ -364,7 +364,7 @@ looksLikeDomainForm x ==
   entry := getCDTEntry(opOf x,true) or return false
   coSig := symbolLassoc('coSig,CDDR entry)
   k := #coSig
-  atom x => k = 1
+  x isnt [.,:.] => k = 1
   k ~= #x => false
   and/[p for key in rest coSig for arg in rest x] where
     p() ==
@@ -717,7 +717,7 @@ dbWordFrom(l,i) ==
 
 conLowerCaseConTran x ==
   ident? x => IFCAR tableValue($lowerCaseConTb, x) or x
-  atom x   => x
+  x isnt [.,:.] => x
   [conLowerCaseConTran y for y in x]
 
 string2Constructor x ==
@@ -726,7 +726,7 @@ string2Constructor x ==
 
 conLowerCaseConTranTryHarder x ==
   ident? x => IFCAR tableValue($lowerCaseConTb,DOWNCASE x) or x
-  atom x   => x
+  x isnt [.,:.] => x
   [conLowerCaseConTranTryHarder y for y in x]
 
 constructorSearchGrep(filter,key,kind) ==
diff --git a/src/interp/br-util.boot b/src/interp/br-util.boot
index 98a290c1..2d0f2e8b 100644
--- a/src/interp/br-util.boot
+++ b/src/interp/br-util.boot
@@ -182,7 +182,7 @@ unMkEvalable u ==
 lisp2HT u == ['"_'",:fn u] where fn u ==
   ident? u => escapeSpecialIds symbolName u
   string? u => escapeString u
-  atom u => systemError()
+  u isnt [.,:.] => systemError()
   ['"_(",:"append"/[fn x for x in u],'")"]
 
 args2HtString(x,:options) ==
@@ -191,7 +191,7 @@ args2HtString(x,:options) ==
   subString(form2HtString(['f,:x],emList),1)
 
 quickForm2HtString(x) ==
-  atom x => STRINGIMAGE x
+  x isnt [.,:.] => STRINGIMAGE x
   form2HtString x
 
 form2HtString(x,:options) ==
@@ -199,7 +199,7 @@ form2HtString(x,:options) ==
   $brief: local := IFCAR IFCDR options --see dbShowOperationsFromConform (lib11)
   fn(x) where
     fn x ==
-      atom x =>
+      x isnt [.,:.] =>
         symbolMember?(x,$FormalMapVariableList) =>
           strconc('"\",symbolName x)
         u := escapeSpecialChars STRINGIMAGE x
@@ -223,17 +223,17 @@ form2HtString(x,:options) ==
       strconc('",",fn first x,fnTailTail rest x)
 
 sexpr2HtString x ==
-  atom x => form2HtString x
+  x isnt [.,:.] => form2HtString x
   strconc('"(",fn x,'")") where fn x ==
     r := rest x
     suffix :=
       null r => '""
-      atom r => strconc('" . ",form2HtString rest x)
+      r isnt [.,:.] => strconc('" . ",form2HtString rest x)
       strconc('" ",fn r)
     strconc(sexpr2HtString first x,suffix)
 
 form2LispString(x) ==
-  atom x =>
+  x isnt [.,:.] =>
     x = '_$ => '"__$"
     symbolMember?(x,$FormalMapVariableList) => strconc('"__", symbolName x)
     string? x => strconc('"_"",x,'"_"")
@@ -246,12 +246,12 @@ form2LispString(x) ==
   strconc(form2LispString first x,args2LispString rest x)
 
 sexpr2LispString x ==
-  atom x => form2LispString x
+  x isnt [.,:.] => form2LispString x
   strconc('"(",fn x,'")") where fn x ==
     r := rest x
     suffix :=
       null r => '""
-      atom r => strconc('" . ",form2LispString rest x)
+      r isnt [.,:.] => strconc('" . ",form2LispString rest x)
       strconc('" ",fn r)
     strconc(sexpr2HtString first x,suffix)
 
@@ -418,7 +418,7 @@ bcConPredTable(u,conname,:options) ==
     htSay '"{"
     bcStarSpace opOf conform
     form :=
-      atom conform => getConstructorForm conform
+      conform isnt [.,:.] => getConstructorForm conform
       conform
     bcConform(form,italicList)
     if extractHasArgs pred is [arglist,:pred] then
diff --git a/src/interp/buildom.boot b/src/interp/buildom.boot
index 511ff5e9..514a6312 100644
--- a/src/interp/buildom.boot
+++ b/src/interp/buildom.boot
@@ -119,7 +119,7 @@ lazyCompareSigEqual(s,tslot,dollar,domain) ==
 
 compareSigEqual(s,t,dollar,domain) ==
   s = t => true
-  atom t =>
+  t isnt [.,:.] =>
     u :=
       t is '$ => dollar
       isSharpVar t =>
@@ -132,7 +132,7 @@ compareSigEqual(s,t,dollar,domain) ==
     u => compareSigEqual(s,u,dollar,domain)
     s = u
   s is '$ => compareSigEqual(dollar,t,dollar,domain)
-  atom s => nil
+  s isnt [.,:.] => nil
   #s ~= #t => nil
   match := true
   for u in s for v in t repeat
@@ -223,7 +223,7 @@ goGet(:l) ==
   val
 
 NRTreplaceLocalTypes(t,dom) ==
-  atom t =>
+  t isnt [.,:.] =>
     not integer? t => t
     t := domainRef(dom,t)
     if cons? t then t := evalDomain t
diff --git a/src/interp/c-doc.boot b/src/interp/c-doc.boot
index cfcd96a9..e3842172 100644
--- a/src/interp/c-doc.boot
+++ b/src/interp/c-doc.boot
@@ -160,7 +160,7 @@ finalizeDocumentation() ==
           for [op,sig] in signatures repeat
             s := formatOpSignature(op,sig)
             sayMSG
-              atom s => ['%x9,s]
+              s isnt [.,:.] => ['%x9,s]
               ['%x9,:s]
         if attributes then
           sayKeyedMsg("S2CD0005",
@@ -169,7 +169,7 @@ finalizeDocumentation() ==
           for x in attributes repeat
             a := form2String x
             sayMSG
-              atom a => ['%x9,a]
+              a isnt [.,:.] => ['%x9,a]
               ['%x9,:a]
       if unusedCommentLineNumbers then
         sayKeyedMsg("S2CD0006",[strconc(STRINGIMAGE bigcnt,'"."),name])
@@ -177,7 +177,7 @@ finalizeDocumentation() ==
           sayMSG ['"   ",:bright n,'"   ",r]
   hn [[:fn(sig,$e),:doc] for [sig,:doc] in docList] where
     fn(x,e) ==
-      atom x => [x,nil]
+      x isnt [.,:.] => [x,nil]
       if #x > 2 then x := TAKE(2,x)
       applySubst(pairList($lisplibForm.args,$FormalMapVariableList),
         macroExpand(x,e))
@@ -241,7 +241,7 @@ transDoc(conname,doclist) ==
 --            checkDocError
 --              ['"_"Related Domain_" has wrong number of arguments: ",x]
 --            nil
---          n=0 and atom x => [x]
+--          n=0 and x isnt [.,:.] => [x]
 --          x
     longline :=
       $x is 'constructor =>
@@ -280,7 +280,7 @@ transformAndRecheckComments(name,lines) ==
   $origin       : local := 'gloss
   $recheckingFlag : local := false
   $exposeFlagHeading : local := 
-    atom name => ['"     -- ",name]
+    name isnt [.,:.] => ['"     -- ",name]
     concat('"     --",formatOpSignature(name.0, escapePercent name.1))
   if not $exposeFlag then sayBrightly $exposeFlagHeading
   u := checkComments(name,lines)
@@ -382,7 +382,7 @@ checkRecordHash u ==
           null parse => checkDocError ['"Unparseable \spadtype: ",s]
           not member(opOf parse,$currentSysList) =>
             checkDocError ['"Bad system command: ",s]
-          atom parse or (parse isnt ['set,arg]) => 'ok  ---assume ok
+          parse isnt [.,:.] or (parse isnt ['set,arg]) => 'ok  ---assume ok
           not spadSysChoose($setOptions,arg) =>
             checkDocError ['"Incorrect \spadsys: ",s]
             entry := tableValue($sysHash,htname) or [nil]
@@ -393,10 +393,10 @@ checkRecordHash u ==
           null parse => checkDocError ['"Unparseable \spadtype: ",s]
           n := checkNumOfArgs parse
           null n => checkDocError ['"Unknown \spadtype: ", s]
-          atom parse and n > 0 => 'skip
+          parse isnt [.,:.] and n > 0 => 'skip
           null (key := checkIsValidType parse) =>
             checkDocError ['"Unknown \spadtype: ", s]
-          atom key => 'ok
+          key isnt [.,:.] => 'ok
           checkDocError ['"Wrong number of arguments: ",form2HtString key]
       else if x in '("\spadop" "\keyword") and (u := checkLookForLeftBrace IFCDR u) and (u := IFCDR u) then
           x := intern checkGetStringBeforeRightBrace u
@@ -428,7 +428,7 @@ checkNumOfArgs conform ==
 ++ The check is down recursively on the argument to the instantiated functor.
 checkIsValidType form == main where
   main() ==
-    atom form => 'ok
+    form isnt [.,:.] => 'ok
     [op,:args] := form
     conname := (constructor? op => op; abbreviation? op)
     null conname => nil
diff --git a/src/interp/c-util.boot b/src/interp/c-util.boot
index ffcbe321..af1888ec 100644
--- a/src/interp/c-util.boot
+++ b/src/interp/c-util.boot
@@ -275,7 +275,7 @@ devaluateList l == [devaluate d for d in l]
  
 devaluateDeeply x ==
   vector? x => devaluate x
-  atom x => x
+  x isnt [.,:.] => x
   [devaluateDeeply y for y in x]
 
 --% Debugging Functions
@@ -347,12 +347,12 @@ mkErrorExpr level ==
       l is [a,b] =>
         highlight(b,a) where
           highlight(b,a) ==
-            atom b =>
+            b isnt [.,:.] =>
               substitute(var,b,a) where
                 var:= makeSymbol strconc(STRINGIMAGE $bright,STRINGIMAGE b,STRINGIMAGE $dim)
             highlight1(b,a) where
               highlight1(b,a) ==
-                atom a => a
+                a isnt [.,:.] => a
                 a is [ =b,:c] => [$bright,b,$dim,:c]
                 [highlight1(b,first a),:highlight1(b,rest a)]
       substitute(bracket rest l,second l,first l)
@@ -549,7 +549,7 @@ unionLike?(m,e) ==
 ++ If `x' designates a store with multiple views, e.g. Union, return
 ++ the collection of those modes.
 unionProperty(x,e) ==
-  atom x => unionLike?(getmode(x,e),e)
+  x isnt [.,:.] => unionLike?(getmode(x,e),e)
   nil
 
 getInverseEnvironment(a,e) ==
@@ -652,7 +652,7 @@ isKnownCategory(c,e) ==
  
 ++ Returns non-nil if `t' is a known type in the environement `e'.
 diagnoseUnknownType(t,e) ==
-  atom t =>
+  t isnt [.,:.] =>
     t in '($ constant) => t
     t' := assoc(t,getDomainsInScope e) => t'
     (m := getmode(t,e)) and isKnownCategory(m,$CategoryFrame) => t
@@ -719,7 +719,7 @@ isConstantId(name,e) ==
 isFalse() == nil
  
 isFluid s ==
-  atom s and char "$" = stringChar(PNAME s,0)
+  s isnt [.,:.] and char "$" = stringChar(PNAME s,0)
  
 isFunction(x,e) ==
   get(x,"modemap",e) or GETL(x,"SPECIAL") or x="case" or getmode(x,e) is [
@@ -764,7 +764,7 @@ isSubset(x,y,e) ==
  
 isDomainInScope(domain,e) ==
   domainList:= getDomainsInScope e
-  atom domain =>
+  domain isnt [.,:.] =>
     symbolMember?(domain,domainList) => true
     not ident? domain or isSomeDomainVariable domain => true
     false
@@ -790,7 +790,7 @@ isAlmostSimple x ==
   transform:=
     fn x where
       fn x ==
-        atom x or null rest x => x
+        x isnt [.,:.] or null rest x => x
         [op,y,:l]:= x
         op="has" => x
         op="is" => x
@@ -813,12 +813,12 @@ incExitLevel u ==
 decExitLevel u ==
   (adjExitLevel(u,1,-1); removeExit0 u) where
     removeExit0 x ==
-      atom x => x
+      x isnt [.,:.] => x
       x is ["exit",0,u] => removeExit0 u
       [removeExit0 first x,:removeExit0 rest x]
  
 adjExitLevel(x,seqnum,inc) ==
-  atom x => x
+  x isnt [.,:.] => x
   x is [op,:l] and op in '(SEQ REPEAT COLLECT) =>
     for u in l repeat adjExitLevel(u,seqnum+1,inc)
   x is ["exit",n,u] =>
@@ -845,7 +845,7 @@ removeEnv t == [t.expr,t.mode,$EmptyEnvironment]  -- t is a triple
 --  [first l,:ordinsert(x,rest l)]
  
 makeNonAtomic x ==
-  atom x => [x]
+  x isnt [.,:.] => [x]
   x
  
 flatten(l,key) ==
@@ -875,7 +875,7 @@ numOfOccurencesOf(x,y) ==
     fn(x,y,n) ==
       null y => 0
       x=y => n+1
-      atom y => n
+      y isnt [.,:.] => n
       fn(x,first y,n)+fn(x,rest y,n)
  
 compilerMessage(msg,args) ==
@@ -888,7 +888,7 @@ printDashedLine() ==
 stackSemanticError(msg,expr) ==
   BUMPERRORCOUNT "semantic"
   if $insideCapsuleFunctionIfTrue then msg:= [$op,": ",:msg]
-  if atom msg then msg:= [msg]
+  if msg isnt [.,:.] then msg:= [msg]
   entry:= [msg,expr]
   if not listMember?(entry,$semanticErrorStack) then $semanticErrorStack:=
     [entry,:$semanticErrorStack]
@@ -929,7 +929,8 @@ stackAndThrow(msg, args == nil) ==
  
 printString x == PRINC (string? x => x; PNAME x)
  
-printAny x == if atom x then printString x else PRIN1 x
+printAny x ==
+  if x isnt [.,:.] then printString x else PRIN1 x
  
 printSignature(before,op,[target,:argSigList]) ==
   printString before
@@ -1018,12 +1019,12 @@ outerProduct l ==
   "append"/[[[x,:y] for y in outerProduct rest l] for x in first l]
  
 sublisR(al,u) ==
-  atom u => u
+  u isnt [.,:.] => u
   y:= rassoc(t:= [sublisR(al,x) for x in u],al) => y
   true => t
  
 substituteOp(op',op,x) ==
-  atom x => x
+  x isnt [.,:.] => x
   [(op=(f:= first x) => op'; f),:[substituteOp(op',op,y) for y in rest x]]
  
 --substituteForFormalArguments(argl,expr) ==
@@ -1032,12 +1033,12 @@ substituteOp(op',op,x) ==
  -- following is only intended for substituting in domains slots 1 and 4
  -- signatures and categories
 sublisV(p,e) ==
-  (atom p => e; suba(p,e)) where
+  (p isnt [.,:.] => e; suba(p,e)) where
     suba(p,e) ==
       string? e => e
       -- no need to descend vectors unless they are categories
       categoryObject? e => LIST2VEC [suba(p,e.i) for i in 0..maxIndex e]
-      atom e => (y:= ASSQ(e,p) => rest y; e)
+      e isnt [.,:.] => (y:= ASSQ(e,p) => rest y; e)
       u:= suba(p,first e)
       v:= suba(p,rest e)
       sameObject?(first e,u) and sameObject?(rest e,v) => e
@@ -1051,7 +1052,7 @@ old2NewModemaps x ==
   x
 
 traceUp() ==
-  atom $x => sayBrightly "$x is an atom"
+  $x isnt [.,:.] => sayBrightly "$x is an atom"
   for y in rest $x repeat
     u:= comp(y,$EmptyMode,$f) =>
       sayBrightly [y,'" ==> mode",'"%b",u.mode,'"%d"]
@@ -1163,7 +1164,7 @@ mutateBindingFormWithUnaryFunction(form,fun) ==
   form isnt [op,inits,:body] and op in '(LET %bind) => form
   for defs in tails inits repeat
     def := first defs
-    atom def => nil -- no initializer
+    def isnt [.,:.] => nil -- no initializer
     def.rest.first := FUNCALL(fun, second def)
   for stmts in tails body repeat
     stmts.first := FUNCALL(fun, first stmts)
@@ -1387,9 +1388,9 @@ proclaimCapsuleFunction(op,sig) ==
           -- we optimize abstractions just as well as builtins.
           r := getRepresentation $e => normalize(r,top?)
           -- Cope with old-style constructor definition
-          atom $functorForm => [$functorForm] 
+          $functorForm isnt [.,:.] => [$functorForm] 
           normalize($functorForm,top?)
-        atom d => 
+        d isnt [.,:.] => 
           top? => "%Thing"
           getmode(d,$e) => "*"
           d
@@ -1412,9 +1413,10 @@ MAKE_-CLOSEDFN_-NAME() ==
 backendCompileNEWNAM: %Form -> %Void
 backendCompileNEWNAM x ==
   atomic? x => nil
-  atom(y := first x) =>
+  y := first x
+  y isnt [.,:.] =>
     backendCompileNEWNAM rest x
-    if y = "CLOSEDFN" then
+    if y is "CLOSEDFN" then
       u := MAKE_-CLOSEDFN_-NAME()
       PUSH([u,second x], $CLOSEDFNS)
       x.first := "FUNCTION"
@@ -1514,7 +1516,7 @@ backendFluidize x ==
     stringChar(symbolName x,0) = char "$" and
       not digit? stringChar(symbolName x,1) => x
   atomic? x => nil
-  first x = "FLUID" => second x
+  first x is "FLUID" => second x
   a := backendFluidize first x
   b := backendFluidize rest x
   a = nil => b
@@ -1663,7 +1665,7 @@ transformToBackendCode x ==
   -- Make it explicitly a sequence of statements if it is not a one liner.
   body := 
     body is [stmt] and
-      (atom stmt
+      (stmt isnt [.,:.]
         or stmt.op in '(SEQ LET LET_*)
           or not CONTAINED("EXIT",stmt)) =>
             body
@@ -1758,7 +1760,7 @@ expandFormTemplate(shell,args,slot) ==
     slot = 0 => "$"
     slot = 2 => "$$"
     expandFormTemplate(shell,args,vectorRef(shell,slot))
-  atom slot => slot
+  slot isnt [.,:.] => slot
   slot is ["local",parm] and (n := isFormal parm) => 
     args.n   -- FIXME: we should probably expand with dual signature
   slot is ["NRTEVAL",val] => val
@@ -1780,7 +1782,7 @@ equalFormTemplate(shell,args,slot,form) ==
   slot is ["QUOTE",val] => 
      string? val or symbol? val or integer? val => val = form
      slot = form
-  atom slot or atom form => form = slot
+  slot isnt [.,:.] or form isnt [.,:.] => form = slot
   #slot ~= #form => false
   and/[equalFormTemplate(shell,args,i,x) for i in slot for x in form]
 
@@ -1816,7 +1818,7 @@ getFunctionTemplate(sig,start,end,shell,args,funDesc) ==
 ++ Subroutine of lookupDefiningFunction.
 lookupInheritedDefiningFunction(op,sig,shell,args,slot) ==
   dom := expandFormTemplate(shell,args,slot)
-  atom dom or dom is ["local",:.] => nil
+  dom isnt [.,:.] or dom is ["local",:.] => nil
   lookupDefiningFunction(op,sig,dom)
 
 ++ Return the name of the function definition that explicitly implements
diff --git a/src/interp/category.boot b/src/interp/category.boot
index ab079f88..1a9073e2 100644
--- a/src/interp/category.boot
+++ b/src/interp/category.boot
@@ -55,7 +55,7 @@ categoryObject? a ==
 ++ envronement `e'.
 isCategoryForm: (%Form,%Env) -> %Boolean
 isCategoryForm(x,e) ==
-  atom x =>
+  x isnt [.,:.] =>
     u := macroExpand(x,e)
     cons? u and categoryForm? u
   categoryForm? x
@@ -95,7 +95,7 @@ mkCategory(domainOrPackage,sigList,attList,domList,PrincipalAncestor) ==
       Prepare2 v ==
         v is '$ => nil
         string? v => nil
-        atom v => [v]
+        v isnt [.,:.] => [v]
         v.op is 'Union =>
           "union"/[Prepare2 x for x in stripUnionTags v.args]
         v.op is 'Mapping => "union"/[Prepare2 x for x in v.args]
@@ -376,7 +376,7 @@ JoinInner(l,$e) ==
   for u in l repeat
     for at in u.2 repeat
       at2:= first at
-      if atom at2 then at2:=[at2]
+      if at2 isnt [.,:.] then at2 := [at2]
         -- the variable $Attributes is built globally, so that true
         -- attributes can be detected without calling isCategoryForm
       symbolMember?(first at2,$Attributes) => nil
diff --git a/src/interp/cattable.boot b/src/interp/cattable.boot
index 231accef..a4c1cdd9 100644
--- a/src/interp/cattable.boot
+++ b/src/interp/cattable.boot
@@ -85,7 +85,7 @@ simpCategoryTable() == main where
       entry := tableValue(_*HASCATEGORY_-HASH_*,key)
       null entry => tableRemove!(_*HASCATEGORY_-HASH_*,key)
       change :=
-        atom opOf entry => simpHasPred entry
+        opOf entry isnt [.,:.] => simpHasPred entry
         [[x,:npred] for [x,:pred] in entry | npred := simpHasPred pred]
       tableValue(_*HASCATEGORY_-HASH_*,key) := change
 
@@ -157,7 +157,8 @@ simpHasAttribute(pred,conform,attr) ==  --eval w/o loading
 simpCatHasAttribute(domform,attr) ==
   conform := getConstructorForm opOf domform
   catval :=  eval mkEvalable conform
-  if atom KDR attr then attr := IFCAR attr
+  if KDR attr isnt [.,:.] then
+    attr := IFCAR attr
   pred :=
     u := LASSOC(attr,catval . 2) => first u
     return false                            --exit: not there
@@ -421,7 +422,7 @@ compressHashTable ht ==
 
 compressSexpr(x,left,right) ==
 -- recursive version of compressHashTable
-  atom x => nil
+  x isnt [.,:.] => nil
   u:= tableValue($found,x) =>
     left => left.first := u
     right => right.rest := u
@@ -439,14 +440,14 @@ squeeze1(l) ==
 -- recursive version of squeezeList
   x:= first l
   y:=
-    atom x => x
+    x isnt [.,:.] => x
     z:= member(x,$found) => first z
     $found:= [x,:$found]
     squeeze1 x
   l.first := y
   x:= rest l
   y:=
-    atom x => x
+    x isnt [.,:.] => x
     z:= member(x,$found) => first z
     $found:= [x,:$found]
     squeeze1 x
diff --git a/src/interp/clammed.boot b/src/interp/clammed.boot
index 479d8ba5..022c31f9 100644
--- a/src/interp/clammed.boot
+++ b/src/interp/clammed.boot
@@ -166,7 +166,7 @@ isLegitimateMode(t,hasPolyMode,polyVarList) ==
   null t        => true    -- a terminating condition with underDomainOf
   t = $EmptyMode => true
   string? t     => true
-  atom t => false
+  t isnt [.,:.] => false
 
   badDoubles := [$QuotientField,:'(Gaussian Complex Polynomial Expression)]
   t is [T1, [T2, :.]] and T1 = T2 and member(T1, badDoubles) => false
@@ -212,7 +212,7 @@ isLegitimateMode(t,hasPolyMode,polyVarList) ==
 
 underDomainOf t ==
   t = $RationalNumber => $Integer
-  atom t => nil
+  t isnt [.,:.] => nil
   d := deconstructT t
   1 = #d => nil
   u := getUnderModeOf(t) => u
diff --git a/src/interp/compiler.boot b/src/interp/compiler.boot
index 8f228742..86a0f629 100644
--- a/src/interp/compiler.boot
+++ b/src/interp/compiler.boot
@@ -182,12 +182,12 @@ comp3(x,m,$e) ==
   e:= $e --for debugging purposes
   m is ["Mapping",:.] => compWithMappingMode(x,m,e)
   m is ["QUOTE",a] => (x=a => [x,m,$e]; nil)
-  string? m => (atom x => (m=x or m=STRINGIMAGE x => [m,m,e]; nil); nil)
+  string? m => (x isnt [.,:.] => (m=x or m=STRINGIMAGE x => [m,m,e]; nil); nil)
   -- In quasiquote mode, x should match exactly
   (y := isQuasiquote m) =>
      y = x => [["QUOTE",x], m, $e]
      nil
-  atom x => compAtom(x,m,e)
+  x isnt [.,:.] => compAtom(x,m,e)
   op:= x.op
   getmode(op,e) is ["Mapping",:ml] and (u:= applyMapping(x,m,e,ml)) => u
   op is ":" => compColon(x,m,e)
@@ -257,7 +257,7 @@ applyMapping([op,:argl],m,e,ml) ==
 --   if argl'="failed" then return nil
 --   mappingHasCategoryTarget => convert([form,first ml,e],m)
 --   form:=
---     not symbolMember?(op,$formalArgList) and atom op =>
+--     not symbolMember?(op,$formalArgList) and op isnt [.,:.] =>
 --       [op',:argl',"$"] where
 --         op':= makeSymbol strconc(STRINGIMAGE $prefix,";",STRINGIMAGE op)
 --     ['%call,["applyFun",op],:argl']
@@ -276,7 +276,7 @@ hasFormalMapVariable(x, vl) ==
 freeVarUsage([.,vars,body],env) ==
   freeList(body,vars,nil,env) where
     freeList(u,bound,free,e) ==
-      atom u =>
+      u isnt [.,:.] =>
         not ident? u => free
         symbolMember?(u,bound) => free
         v := ASSQ(u,free) =>
@@ -305,7 +305,7 @@ freeVarUsage([.,vars,body],env) ==
           for vv in v repeat
             free := freeList(vv,bound,free,e)
         free
-      if atom op then --Atomic functions aren't descended
+      if op isnt [.,:.] then --Atomic functions aren't descended
         u := rest u
       for v in u repeat
         free := freeList(v,bound,free,e)
@@ -695,7 +695,7 @@ compApplication(op,argl,m,T) ==
               for x in argl for m in argml]
     argTl = "failed" => nil
     form:=
-      atom T.expr and 
+      T.expr isnt [.,:.] and 
         not (symbolMember?(op,$formalArgList) or symbolMember?(T.expr,$formalArgList)) and
           null get(T.expr,"value",e) =>
             emitLocalCallInsn(T.expr,[a.expr for a in argTl],e)
@@ -1274,7 +1274,7 @@ compIf(["IF",a,b,c],m,E) ==
   [x,mc,returnEnv]
 
 canReturn(expr,level,exitCount,ValueFlag) ==  --SPAD: exit and friends
-  atom expr => ValueFlag and level=exitCount
+  expr isnt [.,:.] => ValueFlag and level=exitCount
   op := expr.op
   op in '(QUOTE CLOSEDFN) => ValueFlag and level=exitCount
   op is "TAGGEDexit" =>
@@ -1286,7 +1286,7 @@ canReturn(expr,level,exitCount,ValueFlag) ==  --SPAD: exit and friends
     [.,gs,data]:= expr
     (findThrow(gs,data,level,exitCount,ValueFlag) => true) where
       findThrow(gs,expr,level,exitCount,ValueFlag) ==
-        atom expr => nil
+        expr isnt [.,:.] => nil
         expr is ["THROW", =gs,data] => true
             --this is pessimistic, but I know of no more accurate idea
         expr is ["SEQ",:l] =>
@@ -1309,7 +1309,7 @@ canReturn(expr,level,exitCount,ValueFlag) ==  --SPAD: exit and friends
     or/[canReturn(init,level,exitCount,false) for [.,init] in second expr]
        or canReturn(third expr,level,exitCount,ValueFlag)
   --now we have an ordinary form
-  atom op => and/[canReturn(u,level,exitCount,ValueFlag) for u in expr]
+  op isnt [.,:.] => and/[canReturn(u,level,exitCount,ValueFlag) for u in expr]
   systemErrorHere ['"canReturn",expr] --for the time being
 
 ++ We are compiling a conditional expression, type check and generate
@@ -1403,7 +1403,7 @@ getBootType t ==
 ++ Verify that mode `t' is admissible in an external entity signature
 ++ specification, and return its Boot denotation.
 checkExternalEntityType(t,e) ==
-  atom t => 
+  t isnt [.,:.] => 
     stackAndThrow('"Type variable not allowed in import of external entity",nil)
   t' := getBootType t => t'
   stackAndThrow('"Type %1bp is invalid in a foreign signature",[t])
@@ -1559,7 +1559,7 @@ compColon([":",f,t],m,e) ==
     --if inside an expression, ":" means to convert to m "on faith"
   $lhsOfColon: local:= f
   t:=
-    atom t and (t':= assoc(t,getDomainsInScope e)) => t'
+    t isnt [.,:.] and (t':= assoc(t,getDomainsInScope e)) => t'
     isDomainForm(t,e) and not $insideCategoryIfTrue =>
       (if not listMember?(t,getDomainsInScope e) then e:= addDomain(t,e); t)
     isDomainForm(t,e) or isCategoryForm(t,e) => t
@@ -1865,7 +1865,7 @@ resolve(din,dout) ==
 modeEqual(x,y) ==
   -- this is the late modeEqual
   -- orders Unions
-  atom x or atom y => x=y
+  x isnt [.,:.] or y isnt [.,:.] => x=y
   #x ~= #y => nil
   x is ['Union,:xl] and y is ['Union,:yl] =>
     for x1 in xl repeat
@@ -1880,7 +1880,7 @@ modeEqual(x,y) ==
 
 modeEqualSubst(m1,m,e) ==
   modeEqual(m1, m) => true
-  atom m1 => get(m1,"value",e) is [m',:.] and modeEqual(m',m)
+  m1 isnt [.,:.] => get(m1,"value",e) is [m',:.] and modeEqual(m',m)
   m1 is [op,:l1] and m is [=op,:l2]  and # l1 = # l2 =>
 -- Above length test inserted JHD 4:47 on 15/8/86
 -- Otherwise Records can get fouled up - consider expressIdealElt
@@ -2235,7 +2235,7 @@ processInlineRequest(t,e) ==
   T := compOrCroak(t,$EmptyMode,e)
   not isCategoryForm(T.mode,e) =>
     stackAndThrow('"%1b does not designate a domain",[t])
-  atom T.expr =>
+  T.expr isnt [.,:.] =>
     stackWarning('"inline request for type variable %1bp is meaningless",[t])
   nominateForInlining T.expr
 
@@ -2294,7 +2294,7 @@ getIdentity(x,e) ==
 numberize x ==
   x=$Zero => 0
   x=$One => 1
-  atom x => x
+  x isnt [.,:.] => x
   [numberize first x,:numberize rest x]
 
 ++ If there is a local reference to mode `m', return it.  
@@ -2565,11 +2565,11 @@ compUnnamedMapping(parms,source,target,body,env) ==
 gatherParameterList vars == main(vars,nil,nil) where
   main(vars,parms,source) ==
     vars = nil => [reverse! parms,reverse! source]
-    atom vars or vars is [":",:.] => [[x] for x in check vars]
+    vars isnt [.,:.] or vars is [":",:.] => [[x] for x in check vars]
     [v,s] := check first vars
     main(rest vars,[v,:parms],[s,:source])
   check var == 
-    atom var =>
+    var isnt [.,:.] =>
       not ident? var =>
         stackAndThrow('"invalid parameter %1b in lambda expression",[var])
       [checkVariableName var,nil]
diff --git a/src/interp/database.boot b/src/interp/database.boot
index 635e1fea..be5479d8 100644
--- a/src/interp/database.boot
+++ b/src/interp/database.boot
@@ -380,7 +380,7 @@ isDomainSubst u == main where
       [nhead,:isDomainSubst rest u]
     u
   fn(x,alist) ==
-    atom x =>
+    x isnt [.,:.] =>
       ident? x and symbolMember?(x,$PatternVariableList) and (s := findSub(x,alist)) => s
       x
     [first x,:[fn(y,alist) for y in rest x]]
@@ -390,7 +390,7 @@ isDomainSubst u == main where
     findSub(x,rest alist)
 
 signatureTran pred ==
-  atom pred => pred
+  pred isnt [.,:.] => pred
   pred is ["has",D,catForm] and isCategoryForm(catForm,$e) =>
     ['ofCategory,D,catForm]
   [signatureTran p for p in pred]
@@ -402,7 +402,7 @@ interactiveModemapForm mm ==
   mm := replaceVars(COPY mm,$PatternVariableList,$FormalMapVariableList)
   [pattern:=[dc,:sig],pred] := mm
   pred := [fn x for x in pred] where fn x ==
-    x is [a,b,c] and a isnt 'isFreeFunction and atom c => [a,b,[c]]
+    x is [a,b,c] and a isnt 'isFreeFunction and c isnt [.,:.] => [a,b,[c]]
     x
 --pp pred
   [mmpat, patternAlist, partial, patvars] :=
@@ -600,7 +600,7 @@ mkAlistOfExplicitCategoryOps target ==
       [[atomizeOp op,:sig] for x in l | x is ['SIGNATURE,op,sig,:.]]
             where
               atomizeOp op ==
-                atom op => op
+                op isnt [.,:.] => op
                 op is [a] => a
                 keyedSystemError("S2GE0016",
                   ['"mkAlistOfExplicitCategoryOps",'"bad signature"])
@@ -613,7 +613,7 @@ mkAlistOfExplicitCategoryOps target ==
     ['"mkAlistOfExplicitCategoryOps",'"bad signature"])
 
 flattenSignatureList(x) ==
-  atom x => nil
+  x isnt [.,:.] => nil
   x is ['SIGNATURE,:.] => [x]
   x is ['IF,cond,b1,b2] =>
      append(flattenSignatureList b1, flattenSignatureList b2)
@@ -647,7 +647,7 @@ updateDatabase(fname,cname,systemdir?) ==
 
 REMOVER(lst,item) ==
   --destructively removes item from lst
-  atom lst =>
+  lst isnt [.,:.] =>
     lst=item => nil
     lst
   first lst=item => rest lst
diff --git a/src/interp/define.boot b/src/interp/define.boot
index d452065c..11d928fc 100644
--- a/src/interp/define.boot
+++ b/src/interp/define.boot
@@ -137,7 +137,7 @@ makeDomainTemplate vec ==
     item := vectorRef(vec,index)
     null item => nil
     vectorRef(newVec,index) :=
-      atom item => item
+      item isnt [.,:.] => item
       cons? first item => makeGoGetSlot(item,index)
       item   
   $byteVec := "append"/reverse! $byteVec
@@ -255,7 +255,7 @@ NRTmakeCategoryAlist() ==
 
 encodeCatform x ==
   k := NRTassocIndex x => k
-  atom x or atom rest x => x
+  x isnt [.,:.] or rest x isnt [.,:.] => x
   [first x,:[encodeCatform y for y in rest x]]
  
 NRTcatCompare [catform,:pred] == LASSOC(first catform,$levelAlist)
@@ -273,7 +273,7 @@ NRTgetLookupFunction(domform,exCategory,addForm) ==
   domform := applySubst($pairlis,domform)
   addForm := applySubst($pairlis,addForm)
   $why: local := nil
-  atom addForm => 'lookupComplete
+  addForm isnt [.,:.] => 'lookupComplete
   extends := NRTextendsCategory1(domform,exCategory,getExportCategory addForm)
   if null extends then 
     [u,msg,:v] := $why
@@ -362,7 +362,7 @@ substSlotNumbers(form,template,domain) ==
   expandType(form,template,domain)
  
 expandType(lazyt,template,domform) ==
-  atom lazyt => expandTypeArgs(lazyt,template,domform)
+  lazyt isnt [.,:.] => expandTypeArgs(lazyt,template,domform)
   [functorName,:argl] := lazyt
   functorName is ":" =>
     [functorName,first argl,expandTypeArgs(second argl,template,domform)]
@@ -376,7 +376,7 @@ expandTypeArgs(u,template,domform) ==
   integer? u => expandType(templateVal(template, domform, u), template,domform)
   u is ['NRTEVAL,y] => y  --eval  y
   u is ['QUOTE,y] => y
-  atom u => u
+  u isnt [.,:.] => u
   expandType(u,template,domform)
  
 templateVal(template,domform,index) ==
@@ -614,14 +614,14 @@ giveFormalParametersValues(argl,e) ==
 macroExpandInPlace: (%Form,%Env) -> %Form 
 macroExpandInPlace(x,e) ==
   y:= macroExpand(x,e)
-  atom x or atom y => y
+  x isnt [.,:.] or y isnt [.,:.] => y
   x.first := first y
   x.rest := rest y
   x
 
 macroExpand: (%Form,%Env) -> %Form 
 macroExpand(x,e) ==   --not worked out yet
-  atom x =>
+  x isnt [.,:.] =>
     not ident? x or (u := get(x,"macro",e)) = nil => x
     -- Don't expand a functional macro name by itself.
     u is ['%mlambda,:.] => x
@@ -700,7 +700,7 @@ makeCategoryPredicates(form,u) ==
           u is ["has",:.] =>
             insert(applySubst(pairList($tvl,$mvl),u),pl)
           u is [op,:.] and op in '(SIGNATURE ATTRIBUTE) => pl
-          atom u => pl
+          u isnt [.,:.] => pl
           fnl(u,pl)
         fnl(u,pl) ==
           for x in u repeat pl := fn(x,pl)
@@ -717,7 +717,7 @@ mkCategoryPackage(form is [op,:argl],cat,def) ==
   nameForDollar := first SETDIFFERENCE('(S A B C D E F G H I),argl)
   packageArgl := [nameForDollar,:argl]
   capsuleDefAlist := fn(def,nil) where fn(x,oplist) ==
-    atom x => oplist
+    x isnt [.,:.] => oplist
     x is ['DEF,y,:.] => [y,:oplist]
     fn(x.args,fn(x.op,oplist))
   catvec := eval mkEvalableCategoryForm form
@@ -828,7 +828,7 @@ compDefineCategory2(form,signature,specialCases,body,m,e,
 
 mkConstructor: %Form -> %Form
 mkConstructor form ==
-  atom form => ['devaluate,form]
+  form isnt [.,:.] => ['devaluate,form]
   null form.args => ['QUOTE,[form.op]]
   ['%list,MKQ form.op,:[mkConstructor x for x in form.args]]
  
@@ -1199,7 +1199,7 @@ compDefWhereClause(['DEF,form,signature,specialCases,body],m,e) ==
           getmode(a,e) or userError concat(
             '"There is no mode for argument",a,'"of function",form.op)
         transformType x ==
-          atom x => x
+          x isnt [.,:.] => x
           x is [":",R,Rtype] =>
             ($sigAlist:= [[R,:transformType Rtype],:$sigAlist]; x)
           x is ['Record,:.] => x --RDJ 8/83
@@ -1602,7 +1602,7 @@ compileConstructor1 (form:=[fn,[key,vl,:bodyl]]) ==
  
 constructMacro: %Form -> %Form
 constructMacro (form is [nam,[lam,vl,body]]) ==
-  not (and/[atom x for x in vl]) =>
+  not (and/[x isnt [.,:.] for x in vl]) =>
     stackSemanticError(["illegal parameters for macro: ",vl],nil)
   ["XLAM",vl':= [x for x in vl | ident? x],body]
  
@@ -1616,7 +1616,7 @@ modemap2Signature [[.,:sig],:.] == sig
 
 uncons: %Form -> %Form 
 uncons x ==
-  atom x => x
+  x isnt [.,:.] => x
   x is ["CONS",a,b] => [a,:uncons b]
  
 --% CAPSULE
@@ -1758,7 +1758,7 @@ doIt(item,$predl) ==
   item is ["%LET",lhs,rhs,:.] =>
     compOrCroak(item,$EmptyMode,$e) isnt [code,.,$e] =>
       stackSemanticError(["cannot compile assigned value to",:bright lhs],nil)
-    not (code is ["%LET",lhs',rhs',:.] and atom lhs') =>
+    not (code is ["%LET",lhs',rhs',:.] and lhs' isnt [.,:.]) =>
       code is ["PROGN",:.] =>
          stackSemanticError(["multiple assignment ",item," not allowed"],nil)
       item.first := first code
@@ -1865,7 +1865,7 @@ doItIf(item is [.,p,x,y],$predl,$e) ==
    -- conditional compilation
    nils:=ans:=[]
    for u in flp1 repeat -- is =u form always an atom?
-     if atom u or (or/[v is [.,=u,:.] for v in $getDomainCode])
+     if u isnt [.,:.] or (or/[v is [.,=u,:.] for v in $getDomainCode])
        then
          nils:=[u,:nils]
        else
@@ -1896,7 +1896,7 @@ compJoin(["Join",:argl],m,e) ==
           parameters:=
             union("append"/[getParms(y,e) for y in rest x],parameters)
               where getParms(y,e) ==
-                atom y =>
+                y isnt [.,:.] =>
                   isDomainForm(y,e) => [y]
                   nil
                 y is [op,y'] and op in '(LENGTH %llength) => [y,y']
@@ -1905,7 +1905,7 @@ compJoin(["Join",:argl],m,e) ==
         x is ["DomainSubstitutionMacro",pl,body] =>
           (parameters:= union(pl,parameters); body)
         x is ["mkCategory",:.] => x
-        atom x and getmode(x,e)=$Category => x
+        x isnt [.,:.] and getmode(x,e) = $Category => x
         stackSemanticError(["invalid argument to Join: ",x],nil)
         x
   T:= [wrapDomainSub(parameters,["Join",:catList']),$Category,e]
@@ -1949,7 +1949,7 @@ DomainSubstitutionFunction(parameters,body) ==
   if parameters then
     (body := Subst(parameters,body)) where
       Subst(parameters,body) ==
-        atom body =>
+        body isnt [.,:.] =>
           symbolMember?(body,parameters) => MKQ body
           body
         listMember?(body,parameters) =>
@@ -1966,7 +1966,7 @@ DomainSubstitutionFunction(parameters,body) ==
           =>  ['QUOTE,simplifyVMForm body]
         [Subst(parameters,u) for u in body]
   body isnt ["Join",:.] => body
-  atom $definition => body
+  $definition isnt [.,:.] => body
   null $definition.args => body 
            --should not bother if it will only be called once
   name := makeSymbol strconc(KAR $definition,";CAT")
diff --git a/src/interp/diagnostics.boot b/src/interp/diagnostics.boot
index a16cba91..c5075839 100644
--- a/src/interp/diagnostics.boot
+++ b/src/interp/diagnostics.boot
@@ -89,7 +89,7 @@ MESSAGEPRINT_-1 x ==
   PRINC x
 
 MESSAGEPRINT_-2 x ==
-  atom x =>
+  x isnt [.,:.] =>
     not null x =>
       writeString '" . "
       MESSAGEPRINT_-1 x
diff --git a/src/interp/format.boot b/src/interp/format.boot
index 449e1322..cc3d5309 100644
--- a/src/interp/format.boot
+++ b/src/interp/format.boot
@@ -261,7 +261,7 @@ formatOpSymbol(op,sig) ==
   op
 
 formatAttribute x ==
-  atom x => ["  ",x]
+  x isnt [.,:.] => ["  ",x]
   x is [op,:argl] =>
     for x in argl repeat
       argPart:= append!(argPart,concat('",",formatAttributeArg x))
@@ -270,7 +270,7 @@ formatAttribute x ==
 
 formatAttributeArg x ==
   x is '"*" => "_"*_""
-  atom x => formatOpSymbol (x,nil)
+  x isnt [.,:.] => formatOpSymbol (x,nil)
   x is [":",op,["Mapping",:sig]] =>
     concat('"%b",formatOpSymbol(op,sig),": ",'"%d",formatMapping sig)
   prefix2String0 x
@@ -324,7 +324,7 @@ formatSignatureArgs0 sml ==
 --% Conversions to string form
 
 expr2String x ==
-  atom (u:= prefix2String0 x) => u
+  (u:= prefix2String0 x) isnt [.,:.] => u
   strconc/[atom2String y for y in u]
 
 -- exports (this is a badly named bit of sillyness)
@@ -339,7 +339,7 @@ prefix2String0 form ==
   form2StringLocal form
 
 --  SUBRP form => formWrapId BPINAME form
---  atom form =>
+--  form isnt [.,:.] =>
 --    form=$EmptyMode or form=$quadSymbol => formWrapId specialChar 'quad
 --    string? form => formWrapId form
 --    ident? form => 
@@ -361,7 +361,7 @@ form2StringWithPrens form ==
 
 formString u ==
   x := form2String u
-  atom x => STRINGIMAGE x
+  x isnt [.,:.] => STRINGIMAGE x
   strconc/[STRINGIMAGE y for y in x]
 
 form2String u == 
@@ -383,7 +383,7 @@ constructorName con ==
   con
 
 form2String1 u ==
-  atom u => 
+  u isnt [.,:.] => 
     u=$EmptyMode or u=$quadSymbol => formWrapId specialChar 'quad
     ident? u =>
       constructor? u => app2StringWrap(formWrapId u, [u])
@@ -429,10 +429,10 @@ form2String1 u ==
   op = 'AGGLST => tuple2String argl
   op = 'BRACKET =>
     argl' := form2String1 first argl
-    ['"[",:(atom argl' => [argl']; argl'),'"]"]
+    ['"[",:(argl' isnt [.,:.] => [argl']; argl'),'"]"]
   op = 'PAREN =>
     argl' := form2String1 first argl
-    ['"(",:(atom argl' => [argl']; argl'),'")"]
+    ['"(",:(argl' isnt [.,:.] => [argl']; argl'),'")"]
   op = "SIGNATURE" =>
      [operation,sig] := argl
      concat(operation,'": ",formatSignature sig)
@@ -550,7 +550,7 @@ tuple2String argl ==
   if member(string, '("failed" "nil" "prime" "sqfr" "irred"))
     then string := strconc('"_"",string,'"_"")
     else string :=
-      atom string => object2String string
+      string isnt [.,:.] => object2String string
       [f x for x in string]
   for x in rest argl repeat
     if member(x,'("failed" "nil" "prime" "sqfr" "irred")) then
@@ -559,22 +559,22 @@ tuple2String argl ==
   string
  where
   f x ==
-    atom x => object2String x
+    x isnt [.,:.] => object2String x
     -- [f first x,:f rest x]
     [f y for y in x]
 
 script2String s ==
   null s => '""   -- just to be safe
-  if atom s then s := [s]
+  if s isnt [.,:.] then s := [s]
   linearFormatForm(first s, rest s)
 
 linearFormatName x ==
-  atom x => x
+  x isnt [.,:.] => x
   linearFormat x
 
 linearFormat x ==
-  atom x => x
-  x is [op,:argl] and atom op =>
+  x isnt [.,:.] => x
+  x is [op,:argl] and op isnt [.,:.] =>
     argPart:=
       argl is [a,:l] => [a,:"append"/[['",",x] for x in l]]
       nil
@@ -752,7 +752,7 @@ object2Identifier x ==
 blankList x == "append"/[[BLANK,y] for y in x]
 
 pkey keyStuff ==
-    if atom keyStuff then keyStuff := [keyStuff]
+    if keyStuff isnt [.,:.] then keyStuff := [keyStuff]
     allMsgs := ['" "]
     while not null keyStuff repeat
         dbN := nil
@@ -799,16 +799,16 @@ form2FenceQuote x ==
   integer? x => [STRINGIMAGE x]
   symbol? x => [FORMAT(nil, '"|~a|", x)]
   string? x => ['"_"",x,'"_""]
-  atom    x => systemErrorHere ["form2FenceQuote",x]
+  x isnt [.,:.] => systemErrorHere ["form2FenceQuote",x]
   ['"(",:form2FenceQuote first x,:form2FenceQuoteTail rest x]
 
 form2FenceQuoteTail x ==
   null x => ['")"]
-  atom x => ['" . ",:form2FenceQuote x,'")"]
+  x isnt [.,:.] => ['" . ",:form2FenceQuote x,'")"]
   ['" ",:form2FenceQuote first x,:form2FenceQuoteTail rest x]
 
 form2StringList u ==
-  atom (r := form2String u) => [r]
+  (r := form2String u) => [r] isnt [.,:.]
   r
 
 --% Type Formatting Without Abbreviation
@@ -825,7 +825,7 @@ formatUnabbreviatedSig sig ==
 formatUnabbreviatedTuple t ==
   -- t is a list of types
   null t => t
-  atom t => [t]
+  t isnt [.,:.] => [t]
   t0 := formatUnabbreviated t.op
   null rest t => t0
   [:t0,'",",:formatUnabbreviatedTuple rest t]
@@ -833,7 +833,7 @@ formatUnabbreviatedTuple t ==
 formatUnabbreviated t ==
   null t =>
     ['"()"]
-  atom t =>
+  t isnt [.,:.] =>
     [t]
   t is [p,sel,arg] and p = ":" =>
     [sel,'": ",:formatUnabbreviated arg]
diff --git a/src/interp/fortcall.boot b/src/interp/fortcall.boot
index 2c40d76e..2ffe80a1 100644
--- a/src/interp/fortcall.boot
+++ b/src/interp/fortcall.boot
@@ -53,20 +53,20 @@ makeFort(name,args,decls,results,returnType,aspInfo) ==
   dummies := [second(u) for u in args | first u = 0]
   args := [untangle2(u) for u in args] -- lose spad Union representation
     where untangle2 u ==
-      atom (v := rest(u)) => v
+      (v := rest(u)) isnt [.,:.] => v
       first(v)
   userArgs := [u for u in args | not member(u,dummies)]  -- Temporary
   decls := [untangle(u) for u in decls] -- lose spad Union representation
     where untangle u ==
-      [if atom(rest(v)) then rest(v) else _
-        [if atom(w) then w else rest(w) for w in rest(v)] for v in u]
+      [if rest(v) isnt [.,:.] then rest(v) else _
+        [if w isnt [.,:.] then w else rest(w) for w in rest(v)] for v in u]
   makeFort1(name,args,userArgs,dummies,decls,results,returnType,aspInfo)
 
 makeFort1(name,args,userArgs,dummies,decls,results,returnType,aspInfo) ==
   asps := [first(u) for u in aspInfo]
   -- Now reorder the arguments so that all the scalars come first, so
   -- that when we come to deal with arrays we know all the dimensions.
-  scalarArgs := [u for u in args | atom getFortranType(u,decls)]
+  scalarArgs := [u for u in args | getFortranType(u,decls) isnt [.,:.]]
   arrayArgs := [u for u in args | not member(u,scalarArgs)]
   orderedArgs := [:scalarArgs,:arrayArgs]
   file := if $fortranDirectory then
@@ -170,7 +170,7 @@ getFortranType(u,decls) ==
   -- find u in decls, return the given (Fortran) type.
   result := nil
   for d in decls repeat for dec in rest d repeat
-    atom(dec) and dec=u =>
+    dec isnt [.,:.] and dec=u =>
       return( result := first d )
     LISTP(dec) and first(dec)=u =>
       return( result := [first d,:rest dec] )
@@ -225,7 +225,7 @@ writeXDR(v,str,fp) ==
   wl(['"));"],fp)
 
 prefix2Infix(l) ==
-  atom(l) => [l]
+  l isnt [.,:.] => [l]
   #l=2 => [first l,"(",:prefix2Infix second l,")"]
   #l=3 => ["(",:prefix2Infix second l,first l,:prefix2Infix third l,")"]
   error '"Function in array dimensions with more than two arguments"
@@ -283,14 +283,14 @@ spadTypeTTT u ==
 mkQuote l ==
  [addQuote(u)for u in l] where
     addQuote u ==
-      atom u => ['QUOTE,u]
+      u isnt [.,:.] => ['QUOTE,u]
       ["construct",:[addQuote(v) for v in u]]
 
 makeLispList(l) ==
   outputList := []
   for u in l repeat
     outputList := [:outputList, _
-                  if atom(u) then ['QUOTE,u] else [["$elt","Lisp","construct"],_
+                  if u isnt [.,:.] then ['QUOTE,u] else [["$elt","Lisp","construct"],_
                   :makeLispList(u)]]
   outputList
 
@@ -519,10 +519,10 @@ spadify(l,results,decls,names,actual) ==
       if not scalarMember?(0,dims) then els := makeVector(reverse! els,nil)
       spadForms := [makeResultRecord(name,ty,els), :spadForms]
     -- Result is a Boolean Scalar
-    atom fort and ty="logical" =>
+    fort isnt [.,:.] and ty="logical" =>
       spadForms := [makeResultRecord(name,ty,int2Bool fort), :spadForms]
     -- Result is a Scalar
-    atom fort => 
+    fort isnt [.,:.] => 
       spadForms := [makeResultRecord(name,ty,fort),:spadForms]
     error ['"Unrecognised output format: ",fort]
   reverse! spadForms
diff --git a/src/interp/functor.boot b/src/interp/functor.boot
index 106a1557..94619b9d 100644
--- a/src/interp/functor.boot
+++ b/src/interp/functor.boot
@@ -56,7 +56,7 @@ CategoryPrint(D,$e) ==
   for j in 6..maxIndex D repeat
     u := categoryRef(D,j)
     null u => SAY "another domain"
-    atom first u => SAY("Alternate View corresponding to: ",u)
+    first u isnt [.,:.] => SAY("Alternate View corresponding to: ",u)
     PRETTYPRINT u
 
 --%  Domain printing
@@ -212,13 +212,13 @@ getPrincipalView domain ==
   pview
  
 CategoriesFromGDC x ==
-  atom x => nil
+  x isnt [.,:.] => nil
   x is ['%list,a,:b] and a is ['QUOTE,a'] =>
     union([[a']],"union"/[CategoriesFromGDC u for u in b])
   x is ['QUOTE,a] and a is [b] => [a]
  
 compCategories u ==
-  atom u => u
+  u isnt [.,:.] => u
   cons? u.op =>
     error ['"compCategories: need an atom in operator position", u.op]
   u.op in '(Record Union Mapping) =>
@@ -226,7 +226,7 @@ compCategories u ==
     [u.op, :[compCategories1(a,$SetCategory) for a in u.args]]
   u is ['SubDomain,D,.] => compCategories D
   v := get(u.op,'modemap,$e)
-  atom v =>
+  v isnt [.,:.] =>
     error ['"compCategories: could not get proper modemap for operator",u.op]
   if rest v then
     sayBrightly ['"compCategories: ", '"%b", '"Warning", '"%d",
@@ -242,7 +242,7 @@ compCategories u ==
  
 compCategories1(u,v) ==
 -- v is the mode of u
-  atom u => u
+  u isnt [.,:.] => u
   u is [":",x,t] => [u.op,x,compCategories1(t,v)]
   isCategoryForm(v,$e) => compCategories u
   [c,:.] := comp(macroExpand(u,$e),v,$e) => c
@@ -280,7 +280,7 @@ optFunctorBody x ==
     null rest l and null CDAR l =>
             --there is no meat to this conditional form
       pred:= CAAR l
-      atom pred => nil
+      pred isnt [.,:.] => nil
       first pred="HasCategory" => nil
       ['%when,:l]
     ['%when,:l]
@@ -288,12 +288,12 @@ optFunctorBody x ==
  
 optFunctorBodyQuotable u ==
   u = nil or integer? u or string? u => true
-  atom u => false
+  u isnt [.,:.] => false
   u is ['QUOTE,:.] => true
   false
  
 optFunctorBodyRequote u ==
-  atom u => u
+  u isnt [.,:.] => u
   u is ['QUOTE,v] => v
   systemErrorHere ["optFunctorBodyRequote",u]
  
@@ -343,7 +343,7 @@ setVector12 args ==
           freeof($domainShell.4,args1) => nil  
   [['SetDomainSlots124,'$,['QUOTE,args1],['%list,:args2]]]
  where freeof(a,b) ==
-         atom a => null symbolMember?(a,b)
+         a isnt [.,:.] => null symbolMember?(a,b)
          freeof(first a,b) => freeof(rest a,b)
          false
  
@@ -395,7 +395,7 @@ mkDomainFormer x ==
   x
  
 mkTypeForm x ==
-  atom x => mkDevaluate x
+  x isnt [.,:.] => mkDevaluate x
   x.op in '(CATEGORY mkCategory) => MKQ x
   x is [":",selector,dom] =>
     ['%list,MKQ ":",MKQ selector,mkTypeForm dom]
@@ -432,7 +432,7 @@ mkVectorWithDeferral(objects,tag) ==
        for u in objects for count in 0..]]
  
 DescendCodeAdd(base,flag) ==
-  atom base => DescendCodeVarAdd(base,flag)
+  base isnt [.,:.] => DescendCodeVarAdd(base,flag)
   not (modemap:=get(opOf base,'modemap,$CategoryFrame)) =>
       if getmode(opOf base,$e) is ["Mapping",target,:formalArgModes]
          then formalArgs:= take(#formalArgModes,$FormalMapVariableList)
@@ -474,7 +474,7 @@ DescendCodeAdd1(base,flag,target,formalArgs,formalArgModes) ==
   (for u in code repeat
       if update(u,copyvec,[]) then code := remove(code,u))
     where update(code,copyvec,sofar) ==
-      atom code => nil
+      code isnt [.,:.] => nil
       code.op in '(%tref ELT) =>
           copyvec.(third code):=union(copyvec.(third code), sofar)
           true
@@ -591,7 +591,7 @@ ProcessCond cond ==
 TryGDC cond ==
             --sees if a condition can be optimised by the use of
             --information in $getDomainCode
-  atom cond => cond
+  cond isnt [.,:.] => cond
   cond is ['HasCategory,:l] =>
     solved := nil
     for u in $getDomainCode while solved = nil repeat
@@ -679,7 +679,7 @@ InvestigateConditions catvecListMaker ==
   principal' :=
     pessimise $principal where
       pessimise a ==
-        atom a => a
+        a isnt [.,:.] => a
         a is ['SIGNATURE,:.] => a
         a is ['IF,cond,:.] =>
           if not listMember?(cond,$Conditions) then
@@ -703,7 +703,7 @@ InvestigateConditions catvecListMaker ==
     Conds(code,previous) ==
            --each call takes a list of conditions, and returns a list
            --of refinements of that list
-      atom code => [previous]
+      code isnt [.,:.] => [previous]
       code is ['DomainSubstitutionMacro,.,b] => Conds(b,previous)
       code is ['IF,a,b,c] => union(Conds(b,[a,:previous]),Conds(c,previous))
       code is ['PROGN,:l] => "union"/[Conds(u,previous) for u in l]
@@ -760,7 +760,7 @@ InvestigateConditions catvecListMaker ==
   [true,:[LASSOC(ms,list) for ms in masterSecondaries]]
  
 ICformat u ==
-      atom u => u
+      u isnt [.,:.] => u
       u is ["has",:.] => compHasFormat u
       u is ['AND,:l] or u is ['and,:l] =>
         l:= removeDuplicates [ICformat v for [v,:l'] in tails l
@@ -811,7 +811,7 @@ ICformat u ==
       l
  
 partPessimise(a,trueconds) ==
-  atom a => a
+  a isnt [.,:.] => a
   a is ['SIGNATURE,:.] => a
   a is ['IF,cond,:.] => (listMember?(cond,trueconds) => a; nil)
   [partPessimise(first a,trueconds),:partPessimise(rest a,trueconds)]
diff --git a/src/interp/g-cndata.boot b/src/interp/g-cndata.boot
index ce9ff96b..5e0053d9 100644
--- a/src/interp/g-cndata.boot
+++ b/src/interp/g-cndata.boot
@@ -174,7 +174,7 @@ isNameOfType x ==
   constructor? opOf unabbrev x
  
 unabbrev1(u,modeIfTrue) ==
-  atom u =>
+  u isnt [.,:.] =>
     not ident? u => u                    -- surely not constructor abbrev
     modeIfTrue =>
       d:= isDomainValuedVariable u => u
@@ -254,7 +254,7 @@ isConstructorName op ==
  
 nAssocQ(x,l,n) ==
   repeat
-    if atom l then return nil
+    if l isnt [.,:.] then return nil
     if sameObject?(x,first(l).n) then return first l
     l:= rest l
  
diff --git a/src/interp/g-error.boot b/src/interp/g-error.boot
index 718752fd..3d7c58bf 100644
--- a/src/interp/g-error.boot
+++ b/src/interp/g-error.boot
@@ -97,7 +97,7 @@ errorSupervisor1(errorType,errorMsg,$BreakMode) ==
       '"Error with unknown classification"
   msg :=
     errorMsg is ['mathprint, :.] => errorMsg
-    atom errorMsg => ['"   ", errorMsg]
+    errorMsg isnt [.,:.] => ['"   ", errorMsg]
     needsToSplitMessage errorMsg => rest [:['"%l",'"   ",u] for u in errorMsg]
     ['"   ",:errorMsg]
   sayErrorly(errorLabel, msg)
diff --git a/src/interp/g-opt.boot b/src/interp/g-opt.boot
index f571be7f..69c333e3 100644
--- a/src/interp/g-opt.boot
+++ b/src/interp/g-opt.boot
@@ -53,7 +53,7 @@ nominateForInlining dom ==
 ++ return the template of the instantiating functor for
 ++ the domain form `dom'.
 getDomainTemplate dom ==
-  atom dom => nil
+  dom isnt [.,:.] => nil
   getInfovec first dom
 
 ++ Emit code for an indirect call to domain-wide Spad function.  
@@ -160,14 +160,14 @@ optimizeFunctionDef(def) ==
         x is ["THROW", =g,:u] =>
           x.first := "RETURN"
           x.rest := replaceThrowByReturn(u,g)
-        atom x => nil
+        x isnt [.,:.] => nil
         replaceThrowByReturn(first x,g)
         replaceThrowByReturn(rest x,g)
   changeVariableDefinitionToStore(body',args)
   [name,[slamOrLam,args,groupVariableDefinitions body']]
 
 resetTo(x,y) ==
-  atom y => x := y
+  y isnt [.,:.] => x := y
   sameObject?(x,y) => x
   x.first := y.first
   x.rest := y.rest
@@ -179,7 +179,7 @@ simplifyVMForm x ==
   x is '%icst1 => 1
   atomic? x => x
   x.op is 'CLOSEDFN => x
-  atom x.op =>
+  x.op isnt [.,:.] =>
     x is [op,vars,body] and abstractionOperator? op =>
       third(x) := simplifyVMForm body
       x
@@ -199,18 +199,18 @@ subrname u ==
   nil
  
 changeThrowToExit(s,g) ==
-  atom s or s.op in '(QUOTE SEQ REPEAT COLLECT %collect %loop) => nil
+  s isnt [.,:.] or s.op in '(QUOTE SEQ REPEAT COLLECT %collect %loop) => nil
   s is ["THROW", =g,:u] => (s.first := "EXIT"; s.rest := u)
   changeThrowToExit(first s,g)
   changeThrowToExit(rest s,g)
 
 hasNoThrows(a,g) ==
   a is ["THROW", =g,:.] => false
-  atom a => true
+  a isnt [.,:.] => true
   hasNoThrows(first a,g) and hasNoThrows(rest a,g)
 
 changeThrowToGo(s,g) ==
-  atom s or first s is 'QUOTE => nil
+  s isnt [.,:.] or s.op is 'QUOTE => nil
   s is ["THROW", =g,u] =>
     changeThrowToGo(u,g)
     s.first := "PROGN"
@@ -236,7 +236,7 @@ removeNeedlessThrow x ==
 
 optCatch (x is ["CATCH",g,a]) ==
   $InteractiveMode => x
-  atom a => a
+  a isnt [.,:.] => a
   removeNeedlessThrow a
   if a is ["SEQ",:s,["THROW", =g,u]] then
     changeThrowToExit(s,g)
@@ -259,11 +259,11 @@ optSPADCALL(form is ['SPADCALL,:argl]) ==
  
 optCall (x is ['%call,:u]) ==
   u is [['XLAM,vars,body],:args] =>
-    atom vars => body
+    vars isnt [.,:.] => body
     #vars > #args => systemErrorHere ['optCall,x]
     resetTo(x,optXLAMCond applySubst(pairList(vars,args),body))
   [fn,:a] := u
-  atom fn =>
+  fn isnt [.,:.] =>
     opt := fn has OPTIMIZE => resetTo(x,FUNCALL(opt,u))
     resetTo(x,u)
   fn is ['applyFun,name] =>
@@ -332,7 +332,7 @@ EqualBarGensym(x,y) ==
         true
       null x => y is [g] and GENSYMP g
       null y => x is [g] and GENSYMP g
-      atom x or atom y => false
+      x isnt [.,:.] or y isnt [.,:.] => false
       fn(first x,first y) and fn(rest x,rest y)
  
 --Called early, to change IF to conditional form
@@ -348,7 +348,7 @@ optXLAMCond x ==
   x is ['%when,u:= [p,c],:l] =>
     p is '%otherwise => c
     ['%when,u,:optCONDtail l]
-  atom x => x
+  x isnt [.,:.] => x
   x.first := optXLAMCond first x
   x.rest := optXLAMCond rest x
   x
@@ -459,7 +459,7 @@ isSimpleVMForm form ==
 ++ on the program point where it is evaluated. 
 isFloatableVMForm: %Code -> %Boolean
 isFloatableVMForm form ==
-  atom form => form isnt "$"
+  form isnt [.,:.] => form isnt "$"
   form is ["QUOTE",:.] => true
   symbolMember?(form.op, $simpleVMoperators) and
     "and"/[isFloatableVMForm arg for arg in form.args]
@@ -482,7 +482,7 @@ findVMFreeVars form ==
   form isnt [op,:args] => nil  
   op is "QUOTE" => nil
   vars := union/[findVMFreeVars arg for arg in args]
-  atom op => vars
+  op isnt [.,:.] => vars
   union(findVMFreeVars op,vars)
 
 ++ Return true is `var' is the left hand side of an assignment
@@ -584,7 +584,7 @@ optLET u ==
   -- Munge inits into list of dotted-pairs.  Lovely Lisp.
   for defs in tails inits repeat
     def := first defs
-    atom def => systemErrorHere ["optLET",def] -- cannot happen
+    def isnt [.,:.] => systemErrorHere ["optLET",def] -- cannot happen
     def.rest := second def
   applySubst(inits,body)
 
@@ -655,7 +655,7 @@ optCollectVector form ==
 ++ Translate retraction of a value denoted by `e' to sub-domain `m'
 ++ defined by predicate `pred',
 optRetract ["%retract",e,m,pred] ==
-  atom e =>
+  e isnt [.,:.] =>
     cond := simplifyVMForm substitute(e,"#1",pred)
     cond is '%true => e
     ["check-subtype",cond,MKQ m,e]
diff --git a/src/interp/g-util.boot b/src/interp/g-util.boot
index 115aa242..f6584a37 100644
--- a/src/interp/g-util.boot
+++ b/src/interp/g-util.boot
@@ -54,7 +54,7 @@ $AbstractionOperator ==
 ++ Return true if the symbol 's' is used in the form 'x'.  
 usedSymbol?(s,x) ==
   symbol? x => s = x
-  atom x => false
+  x isnt [.,:.] => false
   x is ['QUOTE,:.] => false
   x is [op,parms,:body] and abstractionOperator? op =>
     symbolMember?(s,parms) => false
@@ -145,7 +145,7 @@ noteSubDomainInfo(sub,super,pred) ==
 ++ The transitive closure of the predicate form is returned, where 
 ++ the predicate parameter is `#1'.
 isSubDomain(d1,d2) ==
-  atom d1 or atom d2 => false
+  d1 isnt [.,:.] or d2 isnt [.,:.] => false
 
   -- 1.  Easy, if by syntax constructs.
   d1 is ["SubDomain",=d2,pred] => pred
@@ -284,7 +284,7 @@ addIntSymTabBinding(var,proplist,e is [[curContour,:.],:.]) ==
   e
 
 putMacro(lhs,rhs,e) ==
-  atom lhs => put(lhs,"macro",rhs,e)
+  lhs isnt [.,:.] => put(lhs,"macro",rhs,e)
   parms := [gensym() for p in lhs.args]
   put(lhs.op,"macro",
     ['%mlambda,parms,applySubst(pairList(lhs.args,parms),rhs)],e)
@@ -302,7 +302,7 @@ isQuasiquote m ==
 
 ++ returns the inferred domain for the syntactic object t.
 getTypeOfSyntax t ==
-  atom t => 
+  t isnt [.,:.] => 
     ident? t => '(Identifier)
     (m := getBasicMode t) and not member(m,[$EmptyMode,$NoValueMode]) =>
       ["Literal",m]
@@ -510,9 +510,9 @@ concatList [x,:y] ==
 
 concat1(x,y) ==
   null x => y
-  atom x => (null y => x; atom y => [x,y]; [x,:y])
+  x isnt [.,:.] => (null y => x; y isnt [.,:.] => [x,y]; [x,:y])
   null y => x
-  atom y => [:x,y]
+  y isnt [.,:.] => [:x,y]
   [:x,:y]
 
 --% BOOT ravel and reshape
@@ -528,16 +528,16 @@ boolODDP x == ODDP x
 --% Miscellaneous
 
 freeOfSharpVars x ==
-  atom x => not isSharpVarWithNum x
+  x isnt [.,:.] => not isSharpVarWithNum x
   freeOfSharpVars first x and freeOfSharpVars rest x
 
 listOfSharpVars x ==
-  atom x => (isSharpVarWithNum x => [x]; nil)
+  x isnt [.,:.] => (isSharpVarWithNum x => [x]; nil)
   union(listOfSharpVars first x,listOfSharpVars rest x)
 
 listOfPatternIds x ==
   isPatternVar x => [x]
-  atom x => nil
+  x isnt [.,:.] => nil
   x is ['QUOTE,:.] => nil
   UNIONQ(listOfPatternIds first x,listOfPatternIds rest x)
 
@@ -551,7 +551,7 @@ removeZeroOne x ==
   -- 0 and 1
   x = $Zero => 0
   x = $One => 1
-  atom x => x
+  x isnt [.,:.] => x
   [removeZeroOne first x,:removeZeroOne rest x]
 
 removeZeroOneDestructively t ==
@@ -559,15 +559,15 @@ removeZeroOneDestructively t ==
   -- 0 and 1 destructively
   t = $Zero => 0
   t = $One => 1
-  atom t => t
+  t isnt [.,:.] => t
   RPLNODE(t,removeZeroOneDestructively first t,
     removeZeroOneDestructively rest t)
 
 flattenSexpr s ==
   null s => s
-  atom s => s
+  s isnt [.,:.] => s
   [f,:r] := s
-  atom f => [f,:flattenSexpr r]
+  f isnt [.,:.] => [f,:flattenSexpr r]
   [:flattenSexpr f,:flattenSexpr r]
 
 isLowerCaseLetter c ==
@@ -649,9 +649,9 @@ spadThrowBrightly x ==
   spadThrow()
 
 sublisNQ(al,e) ==
-  atom al => e
+  al isnt [.,:.] => e
   fn(al,e) where fn(al,e) ==
-    atom e =>
+    e isnt [.,:.] =>
       for x in al repeat
         sameObject?(first x,e) => return (e := rest x)
       e
diff --git a/src/interp/ht-root.boot b/src/interp/ht-root.boot
index 1976952c..831d36d4 100644
--- a/src/interp/ht-root.boot
+++ b/src/interp/ht-root.boot
@@ -83,7 +83,7 @@ htSystemVariables() == main where
    where
     functionTail(name,class,var,valuesOrFunction) ==
       val := eval var
-      atom valuesOrFunction =>
+      valuesOrFunction isnt [.,:.] =>
         htMakePage '((domainConditions (isDomain STR (String))))
         htMakePage [['bcLinks,['"reset",'"",'htSetSystemVariableKind,[var,name,nil]]]]
         htMakePage [['bcStrings,[30,STRINGIMAGE val,name,valuesOrFunction]]]
@@ -100,7 +100,7 @@ htSystemVariables() == main where
           htSay('"{\em ",x,'"}\space{1}")
         htMakePage [['bcLispLinks,[x,'" ",'htSetSystemVariable,[variable,x]]]]
     fn(t,al,firstTime) ==
-      atom t => al
+      t isnt [.,:.] => al
       if firstTime then $heading := opOf first t
       fn(rest t,gn(first t,al),firstTime)
     gn(t,al) ==
diff --git a/src/interp/ht-util.boot b/src/interp/ht-util.boot
index 846730c9..46e1fcf1 100644
--- a/src/interp/ht-util.boot
+++ b/src/interp/ht-util.boot
@@ -219,7 +219,7 @@ bcIssueHt line ==
   iht line
 
 mapStringize l ==
-  atom l => l
+  l isnt [.,:.] => l
   l.first := basicStringize first l
   l.rest := mapStringize rest l
   l
diff --git a/src/interp/htcheck.boot b/src/interp/htcheck.boot
index 046ae387..8a0669ef 100644
--- a/src/interp/htcheck.boot
+++ b/src/interp/htcheck.boot
@@ -126,5 +126,5 @@ spadSysBranch(tree,arg) ==  --tree is (msg kind TREEorSomethingElse ...)
   kind = 'TREE => spadSysChoose(tree.4,arg)
   kind = 'LITERALS => member(arg,tree.4)
   kind = 'INTEGER  => integer? arg
-  kind = 'FUNCTION => atom arg
+  kind = 'FUNCTION => arg isnt [.,:.]
   systemError '"unknown tree branch"
diff --git a/src/interp/i-analy.boot b/src/interp/i-analy.boot
index 9f4ce9a7..28c5ea5a 100644
--- a/src/interp/i-analy.boot
+++ b/src/interp/i-analy.boot
@@ -225,7 +225,7 @@ bottomUp t ==
       null tar => [om]
       (r := resolveTM(om,tar)) => [r]
       [om]
-    if atom op then
+    if op isnt [.,:.] then
       opName:= getUnname op
       if isLocallyBound opName then
         putModeSet(op,bottomUpIdentifier(op,opName))
@@ -586,7 +586,7 @@ printableArgModeSetList() ==
   amsl := nil
   for a in reverse $origArgModeSetList repeat
     b := first a
-    if atom b then b := [b]
+    if b isnt [.,:.] then b := [b]
     amsl := ['"%l",b,:amsl]
   if amsl then amsl := rest amsl
   amsl
@@ -787,7 +787,7 @@ bottomUpFormAnyUnionRetract(t,op,opName,argl,amsl) ==
 
   ok := nil
   for m in amsl while not ok repeat
-    if atom first(m) then return nil
+    if first(m) isnt [.,:.] then return nil
     first m = $Any => ok := true
     (first first m = 'Union) => ok := true
   not ok => nil
@@ -811,7 +811,7 @@ bottomUpFormUntaggedUnionRetract(t,op,opName,argl,amsl) ==
 
   ok := nil
   for [m] in amsl while not ok repeat
-    if atom m then return nil
+    if m isnt [.,:.] then return nil
     if m is ['Union, :.] and null getUnionOrRecordTags m then ok := true
   not ok => nil
 
diff --git a/src/interp/i-coerce.boot b/src/interp/i-coerce.boot
index 74e9e0ac..cdb40620 100644
--- a/src/interp/i-coerce.boot
+++ b/src/interp/i-coerce.boot
@@ -212,7 +212,7 @@ retract2Specialization object ==
     null isRectangularList(val',n,m) => nil
     coerceInt(object,['Matrix,D'])
   type is ['Expression,D] =>
-    atom val' => nil          -- certainly not a fraction
+    val' isnt [.,:.] => nil          -- certainly not a fraction
     [num,:den] := val'
     ofCategory(type,$Field) =>
       -- coerceRetract already handles case where den = 1
@@ -424,7 +424,7 @@ canCoerce1(t1,t2) ==
     string? t2 =>
       t1 is ['Variable,v] and (t2 = PNAME(v)) => true
       nil
-    atom t1 or atom t2 => nil
+    t1 isnt [.,:.] or t2 isnt [.,:.] => nil
     null isValidType(t2) => nil
 
     absolutelyCannotCoerce(t1,t2) => nil
@@ -671,7 +671,7 @@ absolutelyCanCoerceByCheating(t1,t2) ==
   -- difference is a subdomain
   isEqualOrSubDomain(t1,t2) => true
   typeIsASmallInteger(t1) and t2 = $Integer => true
-  atom(t1) or atom(t2) => false
+  t1 isnt [.,:.] or t2 isnt [.,:.] => false
   [tl1,:u1] := deconstructT t1
   [tl2,:u2] := deconstructT t2
   tl1 = '(Stream) and tl2 = '(InfiniteTuple) =>
@@ -684,7 +684,7 @@ absolutelyCanCoerceByCheating(t1,t2) ==
 absolutelyCannotCoerce(t1,t2) ==
   -- response of true means "definitely cannot coerce"
   -- this is largely an efficiency hack
-  atom(t1) or atom(t2) => nil
+  t1 isnt [.,:.] or t2 isnt [.,:.] => nil
   t2 = $None => true
   n1   := first t1
   n2   := first t2
@@ -851,13 +851,13 @@ coerceInt1(triple,t2) ==
   (string? t1) and (t1 = unwrap val) =>
     t2 = $OutputForm => objNew(t1,$OutputForm)
     nil
-  atom t1 => nil
+  t1 isnt [.,:.] => nil
 
   if t1 = $AnonymousFunction and (t2 is ['Mapping,target,:margl]) then
     $useCoerceOrCroak := nil
     [.,vars,:body] := unwrap val
     vars :=
-      atom vars => [vars]
+      vars isnt [.,:.] => [vars]
       vars is ["tuple",:.] => rest vars
       vars
     #margl ~= #vars => 'continue
@@ -1234,14 +1234,14 @@ computeTTTranspositions(t1,t2) ==
   reverse! towers
 
 decomposeTypeIntoTower t ==
-  atom t => [t]
+  t isnt [.,:.] => [t]
   d := deconstructT t
   null rest d => [t]
   rd := reverse t
   [reverse rest rd,:decomposeTypeIntoTower first rd]
 
 reassembleTowerIntoType tower ==
-  atom tower => tower
+  tower isnt [.,:.] => tower
   null rest tower => first tower
   [:top,t,s] := tower
   reassembleTowerIntoType [:top,[:t,s]]
diff --git a/src/interp/i-coerfn.boot b/src/interp/i-coerfn.boot
index 93a7afd1..b2d46aee 100644
--- a/src/interp/i-coerfn.boot
+++ b/src/interp/i-coerfn.boot
@@ -1284,7 +1284,7 @@ Sm2PolyType(u,source is [sm,n,S], target is [pol,vl,T]) ==
   -- first want to check case S is Polynomial
   S is ['Polynomial,S'] =>
     -- check to see if variable occurs in any of the terms
-    if atom vl
+    if vl isnt [.,:.]
       then vl' := [vl]
       else vl' := vl
     novars := true
diff --git a/src/interp/i-eval.boot b/src/interp/i-eval.boot
index aae60c58..5626f35c 100644
--- a/src/interp/i-eval.boot
+++ b/src/interp/i-eval.boot
@@ -231,7 +231,7 @@ evalForm(op,opName,argl,mmS) ==
       dc:= first sig
       form :=
         dc='local => --[fun,:form]
-          atom fun =>
+          fun isnt [.,:.] =>
             isLocallyBound fun => ['SPADCALL,:form,fun]
             [fun,:form,nil]
           ['SPADCALL,:form,fun]
@@ -270,7 +270,7 @@ sideEffectedArg?(t,sig,opName) ==
   t = dc
 
 getArgValue(a, t) ==
-  atom a and not vector? a =>
+  a isnt [.,:.] and not vector? a =>
     t' := coerceOrRetract(getBasicObject a,t)
     t' and getValueNormalForm t'
   v := getArgValue1(a, t) => v
diff --git a/src/interp/i-funsel.boot b/src/interp/i-funsel.boot
index d5cbcb91..16b58b74 100644
--- a/src/interp/i-funsel.boot
+++ b/src/interp/i-funsel.boot
@@ -225,7 +225,7 @@ selectMms2(op,tar,args1,args2,$Coerce) ==
     while a repeat
       x:= first a
       a:= rest a
-      atom x => 'iterate
+      x isnt [.,:.] => 'iterate
       mmS := append(mmS, findFunctionInDomain(op,x,tar,args1,args2,nil,nil))
 
     -- step 2. if we didn't get one, trying coercing (if we are
@@ -236,7 +236,7 @@ selectMms2(op,tar,args1,args2,$Coerce) ==
       while a repeat
         x:= first a
         a:= rest a
-        atom x => 'iterate
+        x isnt [.,:.] => 'iterate
         mmS := append(mmS,
           findFunctionInDomain(op,x,tar,args1,args2,$Coerce,nil))
 
@@ -271,7 +271,7 @@ defaultTarget(opNode,op,nargs,args) ==
     target
 
   a1 := first args
-  atom a1 => target
+  a1 isnt [.,:.] => target
   a1f := first a1
 
   nargs = 1 =>
@@ -525,7 +525,7 @@ argCouldBelongToSubdomain(op, nargs) ==
 CONTAINEDisDomain(symbol,cond) ==
 -- looks for [isSubDomain,symbol,[domain]] in cond: returning T or nil
 -- with domain being one of PositiveInteger and NonNegativeInteger
-   atom cond => false
+   cond isnt [.,:.] => false
    cond.op in '(AND OR and or %and %or) =>
        or/[CONTAINEDisDomain(symbol, u) for u in cond.args]
    cond.op is 'isDomain =>
@@ -650,7 +650,7 @@ orderMms(name, mmS,args1,args2,tar) ==
 
 domainDepth(d) ==
   -- computes the depth of lisp structure d
-  atom d => 0
+  d isnt [.,:.] => 0
   MAX(domainDepth(first d)+1,domainDepth(rest d))
 
 hitListOfTarget(t) ==
@@ -907,7 +907,7 @@ matchMmCond(cond) ==
   -- tests the condition, which comes with a modemap
   -- cond is 'T or a list, but I hate to test for 'T (ALBI)
   $domPvar: local := nil
-  atom cond or 
+  cond isnt [.,:.] or 
     cond.op in '(AND and %and) =>
       and/[matchMmCond c for c in cond.args]
     cond.op in '(OR or %or) =>
@@ -1001,7 +1001,7 @@ filterModemapsFromPackages(mms, names, op) ==
 
 
 isTowerWithSubdomain(towerType,elem) ==
-  atom towerType => nil
+  towerType isnt [.,:.] => nil
   dt := deconstructT towerType
   2 ~= #dt => nil
   s := underDomainOf(towerType)
@@ -1035,7 +1035,7 @@ selectMmsGen(op,tar,args1,args2) ==
   -- for common aggregates, use under domain also
   for a in removeDuplicates args repeat
     a =>
-      atom a => nil
+      a isnt [.,:.] => nil
       fa := a.op
       fa in '(Record Union) => nil
       conNames := insert(STRINGIMAGE fa, conNames)
@@ -1235,7 +1235,7 @@ replaceSharpCalls t ==
   doReplaceSharpCalls t
 
 doReplaceSharpCalls t ==
-  atom t => t
+  t isnt [.,:.] => t
   t is ['_#, l] => #l
   t is ['construct,: l] => eval ['LIST,:l]
   [first t,:[ doReplaceSharpCalls u for u in rest t]]
@@ -1491,12 +1491,12 @@ hasCaty(d,cat,SL) ==
         z' := [domArg2(a, S, S') for a in z]
         S1:= unifyStruct(y,z',copy SL)
         if S1 isnt 'failed then S1:=
-          atom cond => S1
+          cond isnt [.,:.] => S1
           ncond := subCopy(cond, S)
           ncond is ["has", =d, =cat] => 'failed
           hasCaty1(ncond,S1)
       S1
-    atom x => SL
+    x isnt [.,:.] => SL
     ncond := subCopy(x, constructSubst d)
     ncond is ["has", =d, =cat] => 'failed
     hasCaty1(ncond, SL)
@@ -1556,7 +1556,7 @@ hasSigAnd(andCls, S0, SL) ==
   SA := 'failed
   for cls in andCls while not dead repeat
     SA :=
-      atom cls => copy SL
+      cls isnt [.,:.] => copy SL
       cls is ["has",a,b] =>
         hasCate(subCopy(a,S0),subCopy(b,S0),copy SL)
       keyedSystemError("S2GE0016",
@@ -1569,7 +1569,7 @@ hasSigOr(orCls, S0, SL) ==
   SA := 'failed
   for cls in orCls until found repeat
     SA :=
-      atom cls => copy SL
+      cls isnt [.,:.] => copy SL
       cls is ["has",a,b] =>
         hasCate(subCopy(a,S0),subCopy(b,S0),copy SL)
       cls is [op,:andCls] and op in '(AND and %and) =>
@@ -1588,7 +1588,7 @@ hasSig(dom,foo,sig,SL) ==
     p := ASSQ(foo,getConstructorOperationsFromDB dom.op) =>
       for [x,.,cond,.] in rest p until S isnt 'failed repeat
         S:=
-          atom cond => copy SL
+          cond isnt [.,:.] => copy SL
           cond is ["has",a,b] =>
             hasCate(subCopy(a,S0),subCopy(b,S0),copy SL)
           cond is [op,:andCls] and op in '(AND and %and) =>
@@ -1641,7 +1641,7 @@ unifyStruct(s1,s2,SL) ==
   s1=s2 => SL
   isPatternVar s1 => unifyStructVar(s1,s2,SL)
   isPatternVar s2 => unifyStructVar(s2,s1,SL)
-  atom s1 or atom s2 => 'failed
+  s1 isnt [.,:.] or s2 isnt [.,:.] => 'failed
   until null s1 or null s2 or SL is 'failed repeat
     SL:= unifyStruct(first s1,first s2,SL)
     s1:= rest s1
@@ -1714,18 +1714,18 @@ printMms(mmS) ==
 
 containsVars(t) ==
   -- tests whether term t contains a * variable
-  atom t => isPatternVar t
+  t isnt [.,:.] => isPatternVar t
   containsVars1(t)
 
 containsVars1(t) ==
   -- recursive version, which works on a list
   [t1,:t2]:= t
-  atom t1 =>
+  t1 isnt [.,:.] =>
     isPatternVar t1 or
-      atom t2 => isPatternVar t2
+      t2 isnt [.,:.] => isPatternVar t2
       containsVars1(t2)
   containsVars1(t1) or
-    atom t2 => isPatternVar t2
+    t2 isnt [.,:.] => isPatternVar t2
     containsVars1(t2)
 
 isPartialMode m ==
@@ -1742,8 +1742,8 @@ getSymbolType var ==
 isEqualOrSubDomain(d1,d2) ==
   -- last 2 parts are for tagged unions (hack for now, RSS)
   (d1=d2) or isSubDomain(d1,d2) or
-    (atom(d1) and ((d2 is ['Variable,=d1]) or (d2 is [=d1])))
-     or (atom(d2) and ((d1 is ['Variable,=d2]) or (d1 is [=d2])))
+    (d1 isnt [.,:.] and ((d2 is ['Variable,=d1]) or (d2 is [=d1])))
+     or (d2 isnt [.,:.] and ((d1 is ['Variable,=d2]) or (d1 is [=d2])))
 
 defaultTypeForCategory(cat, SL) ==
   -- this function returns a domain belonging to cat
diff --git a/src/interp/i-intern.boot b/src/interp/i-intern.boot
index fb9528e3..11199b26 100644
--- a/src/interp/i-intern.boot
+++ b/src/interp/i-intern.boot
@@ -72,7 +72,7 @@ mkAtreeExpandMacros x ==
   -- handle macro expansion. if the macros have args we require that
   -- we match the correct number of args
   if x isnt ["MDEF",:.] and x isnt ["DEF",["macro",:.],:.] then
-    atom x and (m := isInterpMacro x) =>
+    x isnt [.,:.] and (m := isInterpMacro x) =>
       [args,:body] := m
       args => "doNothing"
       x := body
@@ -98,7 +98,7 @@ mkAtree1 x ==
   -- first special handler for making attrib tree
   null x => throwKeyedMsg("S2IP0005",['"NIL"])
   vector? x => x
-  atom x =>
+  x isnt [.,:.] =>
     x in '(%noBranch %noMapVal) => x
     x in '(nil true false) => mkAtree2([x],x,nil)
     x = '_/throwAway =>
@@ -267,7 +267,7 @@ mkAtree3(x,op,argl) ==
       v := mkAtreeNode $immediateDataSymbol
       putValue(v,getBasicObject op)
       v
-    atom op => 
+    op isnt [.,:.] => 
       t := mkAtreeNode op
       putAtree(t, 'flagArgsPos, flagArguments(op,#argl))
       t
@@ -361,7 +361,7 @@ mkAtreeValueOf l ==
   mkAtreeValueOf1 l
 
 mkAtreeValueOf1 l ==
-  null l or atom l or null rest l => l
+  null l or l isnt [.,:.] or null rest l => l
   l is ["valueOf",u] and ident? u =>
     v := mkAtreeNode $immediateDataSymbol
     putValue(v,get(u,"value",$InteractiveFrame) or
@@ -435,7 +435,7 @@ removeBindingI x ==
 
 rempropI(x,prop) ==
   id:=
-    atom x => x
+    x isnt [.,:.] => x
     first x
   getI(id,prop) =>
     recordNewValue(id,prop,nil)
diff --git a/src/interp/i-map.boot b/src/interp/i-map.boot
index e8e9525f..8538c304 100644
--- a/src/interp/i-map.boot
+++ b/src/interp/i-map.boot
@@ -92,7 +92,7 @@ addDefMap(['DEF,lhs,mapsig,.,rhs],pred) ==
   -- a niladic functions.  We try to limit the damage as much as we can.
   defineeIsConstant := false
 
-  if atom lhs then
+  if lhs isnt [.,:.] then
     op := lhs
     putHist(op,'isInterpreterRule,true,$e)
     putHist(op,'isInterpreterFunction,false,$e)
@@ -274,7 +274,7 @@ getIteratorIds itl ==
 makeArgumentIntoNumber x ==
   x=$Zero => 0
   x=$One => 1
-  atom x => x
+  x isnt [.,:.] => x
   x is ["-",n] and integer? n => -n
   [removeZeroOne first x,:removeZeroOne rest x]
 
@@ -405,7 +405,7 @@ outputFormat(x,m) ==
   categoryForm?(m) => x
   isMapExpr x => x
   containsVars x => x
-  atom(x) and first(m) = 'List => x
+  x isnt [.,:.] and first(m) = 'List => x
   (x is ['construct,:.]) and m = '(List (Expression)) => x
   T:= coerceInteractive(objNewWrap(x,maximalSuperType(m)),
     $OutputForm) or return x
@@ -445,7 +445,7 @@ simplifyMapPattern (x,alias) ==
 
 simplifyMapConstructorRefs form ==
   -- try to linear format constructor names
-  atom form => form
+  form isnt [.,:.] => form
   [op,:args] := form
   op in '(exit SEQ) =>
     [op,:[simplifyMapConstructorRefs a for a in args]]
@@ -454,10 +454,10 @@ simplifyMapConstructorRefs form ==
   op in '(_: _:_: _@) =>
     args is [obj,dom] =>
       dom' := prefix2String dom
-      --if atom dom' then dom' := [dom']
+      --if dom' isnt [.,:.] then dom' := [dom']
       --[op,obj,apply(function strconc,dom')]
       dom'' :=
-          atom dom' => dom'
+          dom' isnt [.,:.] => dom'
           null rest dom' => first dom'
           apply(function strconc, dom')
       [op,obj, dom'']
@@ -785,10 +785,10 @@ depthOfRecursion(opName,body) ==
 mapRecurDepth(opName,opList,body) ==
   -- walks over the map body counting depth of recursive calls
   --  expanding the bodies of maps called in body
-  atom body => 0
+  body isnt [.,:.] => 0
   body is [op,:argl] =>
     argc:=
-      atom argl => 0
+      argl isnt [.,:.] => 0
       argl => "MAX"/[mapRecurDepth(opName,opList,x) for x in argl]
       0
     symbolMember?(op,opList) => argc
@@ -895,7 +895,7 @@ nonRecursivePart(opName, funBody) ==
 
 expandRecursiveBody(alreadyExpanded, body) ==
   -- replaces calls to other maps with their bodies
-  atom body =>
+  body isnt [.,:.] =>
     (obj := get(body,'value,$e)) and objVal obj is ["%Map",:mapDef] and
       ((numMapArgs mapDef) = 0) => getMapBody(body,mapDef)
     body
@@ -940,7 +940,7 @@ containsOp(body,op) ==
 
 notCalled(opName,form) ==
   -- returns true if opName is not called in the form
-  atom form => true
+  form isnt [.,:.] => true
   form is [op,:argl] =>
     op=opName => false
     and/[notCalled(opName,x) for x in argl]
@@ -1008,16 +1008,16 @@ findLocalVars(op,form) ==
 
 findLocalVars1(op,form) ==
   -- sets the two lists $localVars and $freeVars
-  atom form =>
+  form isnt [.,:.] =>
     not ident? form or isSharpVarWithNum form => nil
     isLocallyBound form or isFreeVar form => nil
     mkFreeVar($mapName,form)
   form is ['local, :vars] =>
     for x in vars repeat
-      atom x => mkLocalVar(op, x)
+      x isnt [.,:.] => mkLocalVar(op, x)
   form is ['free, :vars] =>
     for x in vars repeat
-      atom x => mkFreeVar(op, x)
+      x isnt [.,:.] => mkFreeVar(op, x)
   form is ["%LET",a,b] =>
     (a is ["tuple",:vars]) and (b is ["tuple",:vals]) =>
       for var in vars for val in vals repeat
@@ -1025,7 +1025,7 @@ findLocalVars1(op,form) ==
     a is ['construct,:pat] =>
       for var in listOfVariables pat repeat mkLocalVar(op,var)
       findLocalVars1(op,b)
-    (atom a) or (a is ['_:,a,.]) =>
+    a isnt [.,:.] or (a is ['_:,a,.]) =>
       mkLocalVar(op,a)
       findLocalVars1(op,b)
     findLocalVars1(op,b)
diff --git a/src/interp/i-object.boot b/src/interp/i-object.boot
index c2bf03ff..73496c23 100644
--- a/src/interp/i-object.boot
+++ b/src/interp/i-object.boot
@@ -113,7 +113,7 @@ removeQuote x ==
 ++ argument to a (library) function call.
 getValueNormalForm obj ==
   val := objVal obj
-  atom val => val
+  val isnt [.,:.] => val
   [op,:argl] := val
   op is "WRAPPED" => MKQ argl
   ident? op and isConstructorName op => 
@@ -125,7 +125,7 @@ getValueNormalForm obj ==
 
 instantiationNormalForm(op,argl) ==
   [op,:[normalVal for arg in argl]] where normalVal() ==
-     atom arg => arg
+     arg isnt [.,:.] => arg
      [h,:t] := arg
      ident? h and isConstructorName h => instantiationNormalForm(h,t)
      MKQ arg
@@ -232,14 +232,14 @@ emptyAtree expr ==
     vectorRef(expr,2) := nil
     vectorRef(expr,3) := nil
     -- kill proplist too?
-  atom expr => nil
+  expr isnt [.,:.] => nil
   for e in expr repeat
     emptyAtree e
 
 
 ++ returns true if x is a leaf VAT object.
 isLeaf x == 
-  atom x     --may be a number or a vector
+  x isnt [.,:.]     --may be a number or a vector
 
 ++ returns the mode of the VAT node x.
 ++ Also used by the algebra interface to the interpreter.
@@ -260,7 +260,7 @@ putMode(x,y) ==
 ++ Also used by the algebra interface to the interperter.
 getValue x ==
   vector? x => vectorRef(x,2)
-  atom x =>
+  x isnt [.,:.] =>
     t := getBasicObject x => t
     keyedSystemError("S2II0001",[x])
   getValue first x
@@ -281,7 +281,7 @@ putValueValue(vec,val) ==
 getUnnameIfCan x ==
   vector? x => vectorRef(x,0)
   x is [op,:.] => getUnnameIfCan op
-  atom x => x
+  x isnt [.,:.] => x
   nil
 
 ++ Returns the node class of x; otherwise raise an error.
@@ -454,7 +454,7 @@ srcPosDisplay(sp) ==
 ++ represented by the VAT `t'.
 getFlagArgsPos t ==
   vector? t => getAtree(t, 'flagArgsPos)
-  atom t => keyedSystemError("S2II0001",[t])
+  t isnt [.,:.] => keyedSystemError("S2II0001",[t])
   getFlagArgsPos first t
 
 --% Transfer of VAT properties.
diff --git a/src/interp/i-output.boot b/src/interp/i-output.boot
index 53949ca0..0f7eb681 100644
--- a/src/interp/i-output.boot
+++ b/src/interp/i-output.boot
@@ -412,7 +412,7 @@ stringWidth u ==
   2+#u
 
 obj2String o ==
-  atom o =>
+  o isnt [.,:.] =>
     string? o => o
     o = " " => '" "
     o = ")" => '")"
@@ -421,7 +421,7 @@ obj2String o ==
   apply(function strconc,[obj2String o' for o' in o])
 
 APP(u,x,y,d) ==
-  atom u => appChar(atom2String u,x,y,d)
+  u isnt [.,:.] => appChar(atom2String u,x,y,d)
   u is [[op,:.],a] and (s:= GETL(op,'PREFIXOP)) =>
     GETL(op,'isSuffix) => appChar(s,x+WIDTH a,y,APP(a,x,y,d))
     APP(a,x+#s,y,appChar(s,x,y,d))
@@ -502,7 +502,7 @@ outputTran x ==
   integer? x =>
     x < 0 => ["-",MINUS x]
     x
-  atom x =>
+  x isnt [.,:.] =>
     x=$EmptyMode => specialChar 'quad
     x
   x is [c,var,mode] and c in '(_pretend _: _:_: _@) =>
@@ -626,7 +626,7 @@ checkArgs(op,tail) ==
   head := []
   while tail repeat
     term := first tail
-    atom term =>
+    term isnt [.,:.] =>
       head := [term,:head]
       tail := rest tail
     not LISTP term => -- never happens?
@@ -725,7 +725,7 @@ outputConstructTran x ==
       b is ['construct,:l] => ['construct,aPart,:l]
       ['BRACKET,['AGGLST,aPart,[":",b]]]
     [op,a,b]
-  atom x => x
+  x isnt [.,:.] => x
   [outputTran first x,:outputConstructTran rest x]
 
 outputTranMatrix x ==
@@ -780,7 +780,7 @@ timesApp(u,x,y,d) ==
       d:= APP(BLANK,x,y,d)
       x:= x+1
     [d,x]:= appInfixArg(arg,x,y,d,rightPrec,"left",nil) --app in a right arg
-    wasSimple:= atom arg and not integer? arg or isRationalNumber arg
+    wasSimple:= arg isnt [.,:.] and not integer? arg or isRationalNumber arg
     wasQuotient:= isQuotient op
     wasNumber:= integer? arg
     lastOp := op
@@ -859,7 +859,7 @@ exptApp([.,a,b],x,y,d) ==
   APP(b,x',y',d)
 
 exptNeedsPren a ==
-  atom a and null (integer? a and a < 0)  => false
+  a isnt [.,:.] and null (integer? a and a < 0)  => false
   key:= keyp a
   key = "OVER" => true  -- added JHD 2/Aug/90
   (key="SUB") or (null GETL(key,"Nud") and null GETL(key,"Led")) => false
@@ -874,8 +874,8 @@ exptWidth [.,a,b] == WIDTH a+WIDTH b+(exptNeedsPren a => 2;0)
 needStar(wasSimple,wasQuotient,wasNumber,cur,op) ==
   wasQuotient or isQuotient op => true
   wasSimple =>
-    atom cur or keyp cur="SUB" or isRationalNumber cur or op="**" or op = "^" or
-      (atom op and not integer? op and null GETL(op,"APP"))
+    cur isnt [.,:.] or keyp cur="SUB" or isRationalNumber cur or op="**" or op = "^" or
+      (op isnt [.,:.] and not integer? op and null GETL(op,"APP"))
   wasNumber =>
     integer?(cur) or isRationalNumber cur or
         ((op="**" or op ="^") and integer?(second cur))
@@ -893,7 +893,7 @@ timesWidth u ==
       w:= w+1
     if infixArgNeedsParens(arg, rightPrec, "left") then w:= w+2
     w:= w+WIDTH arg
-    wasSimple:= atom arg and not integer? arg --or isRationalNumber arg
+    wasSimple:= arg isnt [.,:.] and not integer? arg --or isRationalNumber arg
     wasQuotient:= isQuotient op
     wasNumber:= integer? arg
     firstTime:= nil
@@ -1043,7 +1043,7 @@ outformWidth u ==  --WIDTH as called from OUTFORM to do a COPY
     stringChar(u,0) = char "%" and
       (stringChar(u,1) = char "b" or stringChar(u,1) = char "d") => 1
     #u
-  atom u => # atom2String u
+  u isnt [.,:.] => # atom2String u
   WIDTH COPY u
 
 WIDTH u ==
@@ -1065,12 +1065,12 @@ WIDTH u ==
     -- roughly log2(10). This should return an over-estimate, but for objects
     -- this big does it matter?
     FLOOR(INTEGER_-LENGTH(u)/3.3)
-  atom u => # atom2String u
+  u isnt [.,:.] => # atom2String u
   putWidth u is [[.,:n],:.] => n
   THROW('outputFailure,'outputFailure)
 
 putWidth u ==
-  atom u or u is [[.,:n],:.] and integer? n => u
+  u isnt [.,:.] or u is [[.,:n],:.] and integer? n => u
   op:= keyp u
 --integer? op => nil
   leftPrec:= getBindingPowerOf("left",u)
@@ -1094,7 +1094,7 @@ putWidth u ==
         WIDTH x
     0
   newFirst:=
-    atom (oldFirst:= first u) =>
+    (oldFirst:= first u) isnt [.,:.] =>
       fn:= GETL(oldFirst,"WIDTH") =>
         [oldFirst,:FUNCALL(fn,[oldFirst,:l])]
       if l then ll := rest l else ll := nil
@@ -1155,7 +1155,7 @@ maprin0 x ==
 
 maprinChk x ==
   null $MatrixList => maPrin x
-  atom x and (u:= assoc(x,$MatrixList)) =>
+  x isnt [.,:.] and (u:= assoc(x,$MatrixList)) =>
     $MatrixList := remove($MatrixList,u)
     maPrin deMatrix rest u
   x is ["=",arg,y]  =>     --case for tracing with )math and printing matrices
@@ -1205,7 +1205,7 @@ LargeMatrixp(u,width, dist) ==
   --  sees if there is a matrix wider than 'width' in the next 'dist'
   --  part of u, a sized charybdis structure.
   --  nil if not, first such matrix if there is one
-  atom u => nil
+  u isnt [.,:.] => nil
   CDAR u <= width => nil
        --CDAR is the width of a charybdis structure
   op:=CAAR u
@@ -1270,7 +1270,7 @@ SubstWhileDesizing(u,m) ==
     -- arg. m is always nil (historical: EU directive to increase argument lists 1991/XGII)     
     --Replaces all occurrences of matrix m by name in u
     --Taking out any outdated size information as it goes
-  atom u => u
+  u isnt [.,:.] => u
   [[op,:n],:l]:=u
   --name := RASSOC(u,$MatrixList) => name
   -- doesn't work since RASSOC seems to use an EQ test, and returns the
@@ -1284,7 +1284,7 @@ SubstWhileDesizing(u,m) ==
     PushMatrix u
   l':=SubstWhileDesizingList(l,m)
   -- [op,:l']
-  atom op => [op,:l']
+  op isnt [.,:.] => [op,:l']
   [SubstWhileDesizing(op,m),:l']
 
 --;SubstWhileDesizingList(u,m) ==
@@ -1300,11 +1300,11 @@ SubstWhileDesizing(u,m) ==
 SubstWhileDesizingList(u,m) ==
    u is [a,:b] =>
      res:= 
-       atom a => [a] 
+       a isnt [.,:.] => [a] 
        [SubstWhileDesizing(a,m)] 
      tail:=res
      for i in b repeat
-        if atom i then tail.rest := [i]
+        if i isnt [.,:.] then tail.rest := [i]
         else tail.rest := [SubstWhileDesizing(i,m)]
         tail:=rest tail
      res   
@@ -1345,11 +1345,11 @@ bigopAppAux(bot,top,arg,x,y,d,kind) ==
   xCenter := half(maxWidth-1) + x
   d:=APP(arg,x+2+maxWidth,y,d)
   d:=
-      atom bot and # atom2String bot = 1 => APP(bot,xCenter,y-2,d)
+      bot isnt [.,:.] and # atom2String bot = 1 => APP(bot,xCenter,y-2,d)
       APP(bot,x + half(maxWidth - botWidth),y-2-superspan bot,d)
   if top then
     d:=
-      atom top and # atom2String top = 1 => APP(top,xCenter,y+2,d)
+      top isnt [.,:.] and # atom2String top = 1 => APP(top,xCenter,y+2,d)
       APP(top,x + half(maxWidth - topWidth),y+2+subspan top,d)
   delta := (kind = 'pi => 2; 1)
   opCode :=
@@ -1614,7 +1614,7 @@ outputString(start,linelength,str) ==
 
 outputDomainConstructor form ==
   if VECTORP form then form := devaluate form
-  atom (u:= prefix2String form) => u
+  (u:= prefix2String form) isnt [.,:.] => u
   v:= [object2String(x) for x in u]
   return INTERNL apply(function strconc,v)
 
@@ -1667,7 +1667,7 @@ printBasic x ==
   x=$One => writeInteger(1,$algebraOutputStream)
   x=$Zero => writeInteger(0,$algebraOutputStream)
   ident? x => writeString(symbolName x,$algebraOutputStream)
-  atom x => PRIN1(x,$algebraOutputStream)
+  x isnt [.,:.] => PRIN1(x,$algebraOutputStream)
   PRIN1(x,$algebraOutputStream)
 
 charybdis(u,start,linelength) ==
@@ -1702,8 +1702,8 @@ charyTop(u,start,linelength) ==
   '" "
 
 charyTopWidth u ==
-    atom u => u
-    atom first u => putWidth u
+    u isnt [.,:.] => u
+    first u isnt [.,:.] => putWidth u
     integer? CDAR u => u
     putWidth u
 
@@ -1729,7 +1729,7 @@ sublisMatAlist(m,m1,u) ==
 
 charyTrouble1(u,v,start,linelength) ==
   integer? u => outputNumber(start,linelength,atom2String u)
-  atom u => outputString(start,linelength,atom2String u)
+  u isnt [.,:.] => outputString(start,linelength,atom2String u)
   sameObject?(x:= keyp u,'_-) => charyMinus(u,v,start,linelength)
   x in '(_+ _* AGGLST) => charySplit(u,v,start,linelength)
   x='EQUATNUM => charyEquatnum(u,v,start,linelength)
@@ -1845,8 +1845,8 @@ scylla(n,v) ==
   nil
 
 keyp(u) ==
-  atom u => nil
-  atom first u => first u
+  u isnt [.,:.] => nil
+  first u isnt [.,:.] => first u
   CAAR u
 
 absym x ==
@@ -1866,10 +1866,10 @@ aggwidth u ==
 argsapp(u,x,y,d) == appargs(rest u,x,y,d)
 
 subspan u ==
-  atom u => 0
+  u isnt [.,:.] => 0
   integer? rest u => subspan first u
   (cons? first u             and_
-   atom CAAR u           and_
+   CAAR u isnt [.,:.]        and_
    not integer? CAAR u    and_
    GETL(CAAR u, 'SUBSPAN)    )    =>
    APPLX(GETL(CAAR u, 'SUBSPAN), [u])
@@ -1878,10 +1878,10 @@ subspan u ==
 agggsub u == subspan rest u
 
 superspan u ==
-  atom u => 0
+  u isnt [.,:.] => 0
   integer? rest u => superspan first u
   (cons? first u               and_
-   atom CAAR u             and_
+   CAAR u isnt [.,:.]          and_
    not integer? CAAR u      and_
    GETL(CAAR u, 'SUPERSPAN)    )    =>
    APPLX(GETL(CAAR u, 'SUPERSPAN), [u])
@@ -2362,8 +2362,8 @@ qTWidth(u) ==
   2 + WIDTH second u
 
 remWidth(x) ==
-  atom x => x
-  true => [(atom first x => first x; true => CAAR x),
+  x isnt [.,:.] => x
+  true => [(first x isnt [.,:.] => first x; true => CAAR x),
               :[remWidth y for y in rest x]]
 
 subSub(u) ==
@@ -2554,7 +2554,7 @@ mathPrint u ==
    PSTRING u; nil)
 
 mathPrintTran u ==
-  atom u => u
+  u isnt [.,:.] => u
   true =>
     for x in tails u repeat
           x.first := mathPrintTran first x
@@ -2601,11 +2601,11 @@ primaryForm2String x ==
     x = "$" => '"%"
     x = "$$" => '"%%"
     symbolName x
-  atom x => toString x
+  x isnt [.,:.] => toString x
   strconc('"(",inputForm2String x, '")")
 
 callForm2String x ==
-  atom x => primaryForm2String x
+  x isnt [.,:.] => primaryForm2String x
   [op,:args] := x
 
   member(op,$allClassicOps) => primaryForm2String x
@@ -2674,7 +2674,7 @@ parms2String x ==
       strconc(first xs, '", ")
 
 inputForm2String x ==
-  atom x => primaryForm2String x
+  x isnt [.,:.] => primaryForm2String x
   [op,:args] := x
   isUnaryPrefix op and #args = 1 => unaryForm2String x
   #args = 2 =>
diff --git a/src/interp/i-resolv.boot b/src/interp/i-resolv.boot
index a8c4f44c..4a0f08eb 100644
--- a/src/interp/i-resolv.boot
+++ b/src/interp/i-resolv.boot
@@ -326,7 +326,7 @@ resolveTTRed2(t1,t2,TL) ==
 resolveTTRed3(t) ==
   -- recursive resolveTTRed which handles all subterms of the form
   -- (Resolve t1 t2) or subterms which have to be interpreted
-  atom t => t
+  t isnt [.,:.] => t
   t is ['Resolve,a,b] =>
     ( t1 := resolveTTRed3 a ) and ( t2 := resolveTTRed3 b ) and
       resolveTT1(t1,t2)
@@ -339,7 +339,7 @@ resolveTTRed3(t) ==
   t is ['VarEqual,a,b] => (a = b) and a
   t is ['SetEqual,a,b] =>
     (and/[member(x,a) for x in b] and "and"/[member(x,b) for x in a]) and a
-  [( atom x and x ) or ((not cs and x and not interpOp? x and x)
+  [(x isnt [.,:.] and x ) or ((not cs and x and not interpOp? x and x)
     or resolveTTRed3 x) or return nil
       for x in t for cs in getDualSignatureFromDB first t ]
 
@@ -448,7 +448,7 @@ matchUpToPatternVars(pat,form,patAlist) ==
     patAlist := [[pat,:form],:patAlist]
     true
   cons?(pat) =>
-    atom form => nil
+    form isnt [.,:.] => nil
     matchUpToPatternVars(first pat, first form,patAlist) and
       matchUpToPatternVars(rest pat, rest form,patAlist)
   nil
@@ -491,7 +491,7 @@ resolveTM1(t,m) ==
         t=rest p and t
       $Subst := [[m,:t],:$Subst]
       t
-    atom(t) or atom(m) => nil
+    t isnt [.,:.] or m isnt [.,:.] => nil
     (t is ['Record,:tr]) and (m is ['Record,:mr]) and
       (tt := resolveTMRecord(tr,mr)) => tt
     t is ['Record,:.] or m is ['Record,:.] => nil
@@ -678,7 +678,7 @@ resolveTMRed(t,m) ==
 resolveTMRed1(t) ==
   -- recursive resolveTMRed which handles all subterms of the form
   -- (Resolve a b)
-  atom t => t
+  t isnt [.,:.] => t
   t is ['Resolve,a,b] =>
     ( a := resolveTMRed1 a ) and ( b := resolveTMRed1 b ) and
       resolveTM1(a,b)
@@ -692,7 +692,7 @@ resolveTMRed1(t) ==
     "and"/[member(x,a) for x in b] and SETDIFFERENCE(a,b)
   t is ['SimpleAlgebraicExtension,a,b,p] =>  -- this is a hack. RSS
     ['SimpleAlgebraicExtension, resolveTMRed1 a, resolveTMRed1 b,p]
-  [( atom x and x ) or resolveTMRed1 x or return nil for x in t]
+  [(x isnt [.,:.] and x ) or resolveTMRed1 x or return nil for x in t]
 
 --% Type and Mode Representation
 
diff --git a/src/interp/i-special.boot b/src/interp/i-special.boot
index 54729eb6..073c2cbd 100644
--- a/src/interp/i-special.boot
+++ b/src/interp/i-special.boot
@@ -941,7 +941,7 @@ mkIterZippedFun(indexList,funBody,zipType,$localVars) ==
   vec
 
 subVecNodes(new,old,form) ==
-  atom form =>
+  form isnt [.,:.] =>
     (vector? form) and (form.0 = old) => new
     form
   [subVecNodes(new,old,first form), :subVecNodes(new,old,rest form)]
@@ -1250,14 +1250,14 @@ isPolynomialMode m ==
   nil
 
 containsPolynomial m ==
-  atom m => nil
+  m isnt [.,:.] => nil
   [d,:.] := m
   symbolMember?(d,$univariateDomains) or symbolMember?(d,$multivariateDomains) or
     d in '(Polynomial RationalFunction) => true
   (m' := underDomainOf m) and containsPolynomial m'
 
 containsVariables m ==
-  atom m => nil
+  m isnt [.,:.] => nil
   [d,:.] := m
   symbolMember?(d,$univariateDomains) or symbolMember?(d,$multivariateDomains) => true
   (m' := underDomainOf m) and containsVariables m'
@@ -1367,7 +1367,7 @@ upDollar t ==
   if f = $immediateDataSymbol then
     f := objValUnwrap coerceInteractive(getValue form,$OutputForm)
     if f = '(construct) then f := "nil"
-  atom form and (f ~= $immediateDataSymbol) =>
+  form isnt [.,:.] and (f ~= $immediateDataSymbol) =>
     type := constantInDomain?([f],t) =>
       type ~= true => findConstantInDomain(op,f,type,t)
       -- Ambiguous constant.  FIXME: try to narrow before giving up.
@@ -1413,7 +1413,7 @@ upDollarTuple(op, f, t, t2, args, nargs) ==
 
 upLispCall(op,t) ==
   -- process $Lisp calls
-  if atom t then code:=getUnname t else
+  if t isnt [.,:.] then code:=getUnname t else
     [lispOp,:argl]:= t
     null functionp lispOp.0 =>
       throwKeyedMsg("S2IS0024",[lispOp.0])
@@ -1672,7 +1672,7 @@ removeConstruct pat ==
   -- removes the "construct" from the beginning of patterns
   if pat is ["construct",:p] then pat:=p
   if pat is ["cons", a, b] then pat := [a, [":", b]]
-  atom pat => pat
+  pat isnt [.,:.] => pat
   pat.first := removeConstruct first pat
   pat.rest := removeConstruct rest pat
   pat
@@ -1973,7 +1973,7 @@ unVectorize body ==
     name := getUnname body
     name ~= $immediateDataSymbol => name
     objValUnwrap getValue body
-  atom body => body
+  body isnt [.,:.] => body
   body is [op,:argl] =>
     newOp:=unVectorize op
     if newOp = 'SUCHTHAT then newOp := "|"
@@ -2098,7 +2098,7 @@ NRTcompiledLookup(op,sig,dom) ==
   compiledLookupCheck(op,sig,dom)
 
 NRTtypeHack t ==
-  atom t => t
+  t isnt [.,:.] => t
   first t = '_# => # second t
   [first t,:[NRTtypeHack tt for tt in rest t]]
 
@@ -2411,7 +2411,7 @@ upwhere t ==
   [env,:e] := upwhereClause(clause,$env,$e)
   tree := upwhereMkAtree(tree,env,e)
   if x := getAtree(op,'dollar) then
-    atom tree => throwKeyedMsg("S2IS0048",nil)
+    tree isnt [.,:.] => throwKeyedMsg("S2IS0048",nil)
     putAtree(first tree,'dollar,x)
   upwhereMain(tree,env,e)
   val := getValue tree
diff --git a/src/interp/i-syscmd.boot b/src/interp/i-syscmd.boot
index 1cbdc3a7..37724492 100644
--- a/src/interp/i-syscmd.boot
+++ b/src/interp/i-syscmd.boot
@@ -968,7 +968,7 @@ displayType($op,u,omitVariableNameIfTrue) ==
     sayMSG ['"   Type of value of ",
         fixObjectForPrinting PNAME $op,'":  (none)"]
   type := prefix2String objMode(u)
-  if atom type then type := [type]
+  if type isnt [.,:.] then type := [type]
   sayMSG concat ['"   Type of value of ",fixObjectForPrinting PNAME $op,'": ",:type]
   nil
 
@@ -984,7 +984,7 @@ displayValue($op,u,omitVariableNameIfTrue) ==
     rhs := '":  "
     strconc('"Value of ", PNAME $op,'": ")
   labmode := prefix2String objMode(u)
-  if atom labmode then labmode := [labmode]
+  if labmode isnt [.,:.] then labmode := [labmode]
   ident? expr and getConstructorKindFromDB expr = "domain" =>
     sayMSG concat('"   ",label,labmode,rhs,form2String expr)
   mathprint ['CONCAT,label,:labmode,rhs,
@@ -1091,7 +1091,7 @@ frameSpad2Cmd args ==
   arg  := selectOptionLC(first args,frameArgs,'optionError)
   args := rest args
   if args is [a] then args := a
-  if atom args then args := object2Identifier args
+  if args isnt [.,:.] then args := object2Identifier args
   arg is 'drop  =>
     args and cons?(args) => throwKeyedMsg("S2IZ0017",[args])
     closeInterpreterFrame(args)
@@ -1229,7 +1229,7 @@ displayFrameNames() ==
 
 importFromFrame args ==
   -- args should have the form [frameName,:varNames]
-  if args and atom args then args := [args]
+  if args and args isnt [.,:.] then args := [args]
   null args => throwKeyedMsg("S2IZ0073",nil)
   [fname,:args] := args
   not member(fname,frameNames()) =>
@@ -1705,7 +1705,7 @@ readHiFi(n) ==
   if $useInternalHistoryTable
   then
     pair := assoc(n,$internalHistoryTable)
-    atom pair => keyedSystemError("S2IH0034",nil)
+    pair isnt [.,:.] => keyedSystemError("S2IH0034",nil)
     vec := rest pair
   else
     HiFi:= RDEFIOSTREAM ['(MODE . INPUT),['FILE,:histFileName()]]
@@ -2124,15 +2124,15 @@ reportOperations(oldArg,u) ==
     sayKeyedMsg("S2IZ0064",nil)
   u isnt ['Record,:.] and u isnt ['Union,:.] and
     null(isNameOfType u) and u isnt ['typeOf,.] =>
-      if atom oldArg then oldArg := [oldArg]
+      if oldArg isnt [.,:.] then oldArg := [oldArg]
       sayKeyedMsg("S2IZ0063",nil)
       for op in oldArg repeat
         sayKeyedMsg("S2IZ0062",[opOf op])
   (v := isDomainValuedVariable u) =>  reportOpsFromUnitDirectly0 v
   unitForm:=
-    atom u => opOf unabbrev u
+    u isnt [.,:.] => opOf unabbrev u
     unabbrev u
-  atom unitForm => reportOpsFromLisplib0(unitForm,u)
+  unitForm isnt [.,:.] => reportOpsFromLisplib0(unitForm,u)
   unitForm' := evaluateType unitForm
   tree := mkAtree removeZeroOneDestructively unitForm
   (unitForm' := isType tree) => reportOpsFromUnitDirectly0 unitForm'
@@ -2220,7 +2220,7 @@ reportOpsFromUnitDirectly unitForm ==
             $CategoryFrame)
           sigList := removeDuplicates MSORT
                       [[[a,b],true,slot c] for [a,b,c] in funlist]
-                             where slot c == (atom c => [c,0,1]; c)
+                             where slot c == (c isnt [.,:.] => [c,0,1]; c)
         else
           sigList:= removeDuplicates MSORT getOplistForConstructorForm unitForm
       say2PerLine [formatOperation(x,unit) for x in sigList]
diff --git a/src/interp/i-util.boot b/src/interp/i-util.boot
index 4084ff67..136c61b9 100644
--- a/src/interp/i-util.boot
+++ b/src/interp/i-util.boot
@@ -46,7 +46,7 @@ $intTopLevel ==
  
 inputPrompt str ==
   -- replaces older INPUT-PROMPT
-  atom (x := $SCREENSIZE()) => nil
+  (x := $SCREENSIZE()) isnt [.,:.] => nil
   p := first(x) - 2
   y := $OLDLINE
   SETQ($OLDLINE,nil)
diff --git a/src/interp/interop.boot b/src/interp/interop.boot
index 561edc19..5067a3f2 100644
--- a/src/interp/interop.boot
+++ b/src/interp/interop.boot
@@ -194,7 +194,7 @@ oldAxiomPreCategoryParents(catform,dom) ==
       [eval quoteCatOp cat for [cat,:pred] in parents | eval pred])
 
 quoteCatOp cat == 
-   atom cat => MKQ cat
+   cat isnt [.,:.] => MKQ cat
    ['LIST, MKQ first cat,: rest cat]
 
 
@@ -282,7 +282,7 @@ depthAssoc x ==
 getCatAncestors x ==  [CAAR y for y in parentsOf opOf x]
  
 listOfEntries form ==
-  atom form => form
+  form isnt [.,:.] => form
   form is [op,:l] =>
     op is 'Join => "append"/[listOfEntries x for x in l]
     op is 'CATEGORY => listOfCategoryEntries rest l
diff --git a/src/interp/lisp-backend.boot b/src/interp/lisp-backend.boot
index ceeed354..bd6aa7f5 100644
--- a/src/interp/lisp-backend.boot
+++ b/src/interp/lisp-backend.boot
@@ -82,7 +82,7 @@ expandSTEP(id,lo,step,final)==
     loopvar := [:loopvar,[g1,step]]
     g1
   final :=
-    atom final => final
+    final isnt [.,:.] => final
     final is [hi] and atomic? hi => hi
     g2 := gensym()
     loopvar := [:loopvar,[g2,:final]]
diff --git a/src/interp/lisplib.boot b/src/interp/lisplib.boot
index 7cae8dcb..cc766b57 100644
--- a/src/interp/lisplib.boot
+++ b/src/interp/lisplib.boot
@@ -101,7 +101,7 @@ makePredicateBitVector pl ==   --called by buildFunctor
   $predGensymAlist := nil --bound by buildFunctor, used by optHas
   for p in removeAttributePredicates pl repeat
     pred := simpBool transHasCode p
-    atom pred => 'skip                --skip over T and nil
+    pred isnt [.,:.] => 'skip                --skip over T and nil
     if isHasDollarPred pred then 
       lasts := insert(pred,lasts)
       for q in stripOutNonDollarPreds pred repeat firsts := insert(q,firsts)
@@ -151,7 +151,7 @@ removeAttributePredicates pl ==
     fnl p == [fn x for x in p]
  
 transHasCode x ==
-  atom x => x
+  x isnt [.,:.] => x
   op := x.op
   op in '(HasCategory HasAttribute) => x
   op="has" => compHasFormat x
@@ -159,7 +159,7 @@ transHasCode x ==
  
 mungeAddGensyms(u,gal) ==
   ['%list,:[fn(x,gal,0) for x in u]] where fn(x,gal,n) ==
-    atom x => x
+    x isnt [.,:.] => x
     g := LASSOC(x,gal) =>
       n = 0 => ["%LET",g,x]
       g
@@ -626,8 +626,8 @@ mergeSignatureAndLocalVarAlists(signatureAlist, localVarAlist) ==
     [funcName, :signature] in signatureAlist]
  
 Operators u ==
-  atom u => []
-  atom first u =>
+  u isnt [.,:.] => []
+  first u isnt [.,:.] =>
     answer:="union"/[Operators v for v in rest u]
     symbolMember?(first u,answer) => answer
     [first u,:answer]
diff --git a/src/interp/modemap.boot b/src/interp/modemap.boot
index fd5d56bb..0f393f5c 100644
--- a/src/interp/modemap.boot
+++ b/src/interp/modemap.boot
@@ -45,7 +45,7 @@ $forceAdd := false
 --   or to get the current domains in scope;
  
 addDomain(domain,e) ==
-  atom domain =>
+  domain isnt [.,:.] =>
     domain="$EmptyMode" => e
     domain="$NoValueMode" => e
     not ident? domain or 2 < #(s:= STRINGIMAGE domain) and
@@ -139,7 +139,7 @@ addEltModemap(op,mc,sig,pred,fn,e) ==
          then $e:= makeLiteral(id,$e)
          else e:= makeLiteral(id,e)
       addModemap1(op,mc,[:lt,id],pred,fn,e)
-    -- atom sel => systemErrorHere '"addEltModemap"
+    -- sel isnt [.,:.] => systemErrorHere '"addEltModemap"
     addModemap1(op,mc,sig,pred,fn,e)
   op='setelt and sig is [:lt,sel,v] =>
     string? sel =>
@@ -148,7 +148,7 @@ addEltModemap(op,mc,sig,pred,fn,e) ==
          then $e:= makeLiteral(id,$e)
          else e:= makeLiteral(id,e)
       addModemap1(op,mc,[:lt,id,v],pred,fn,e)
-    -- atom sel => systemError '"addEltModemap"
+    -- sel isnt [.,:.] => systemError '"addEltModemap"
     addModemap1(op,mc,sig,pred,fn,e)
   systemErrorHere '"addEltModemap"
  
@@ -213,7 +213,7 @@ augModemapsFromDomain(name,functorForm,e) ==
 augModemapsFromDomain1(name,functorForm,e) ==
   property(KAR functorForm,"makeFunctionList") =>
     addConstructorModemaps(name,functorForm,e)
-  atom functorForm and (catform := getmode(functorForm,e)) =>
+  functorForm isnt [.,:.] and (catform := getmode(functorForm,e)) =>
     augModemapsFromCategory(name,name,functorForm,catform,e)
   mappingForm := getmodeOrMapping(KAR functorForm,e) =>
     ["Mapping",categoryForm,:functArgTypes] := mappingForm
@@ -275,7 +275,7 @@ evalAndSub(domainName,viewName,functorForm,form,$e) ==
   [substAlist,$e]
  
 getOperationAlist(name,functorForm,form) ==
-  if atom name and niladicConstructorFromDB name then 
+  if name isnt [.,:.] and niladicConstructorFromDB name then 
     functorForm:= [functorForm]
   (u:= isFunctor functorForm) and not
     ($insideFunctorIfTrue and first functorForm=first $functorForm) => u
@@ -359,7 +359,7 @@ addInformation(m,$e) ==
   info m where
     info m ==
       --Processes information from a mode declaration in compCapsule
-      atom m => nil
+      m isnt [.,:.] => nil
       m is ["CATEGORY",.,:stuff] => for u in stuff repeat addInfo u
       m is ["Join",:stuff] => for u in stuff repeat info u
       nil
@@ -372,15 +372,15 @@ addInfo u ==
   $Information:= [formatInfo u,:$Information]
  
 formatInfo u ==
-  atom u => u
+  u isnt [.,:.] => u
   u is ["SIGNATURE",:v] => ["SIGNATURE","$",:v]
   u is ["PROGN",:l] => ["PROGN",:[formatInfo v for v in l]]
   u is ["ATTRIBUTE",v] =>
  
     -- The parser can't tell between those attributes that really
     -- are attributes, and those that are category names
-    atom v and isCategoryForm([v],$e) => ["has","$",[v]]
-    atom v => ["ATTRIBUTE","$",v]
+    v isnt [.,:.] and isCategoryForm([v],$e) => ["has","$",[v]]
+    v isnt [.,:.] => ["ATTRIBUTE","$",v]
     isCategoryForm(v,$e) => ["has","$",v]
     ["ATTRIBUTE","$",v]
   u is ["IF",a,b,c] =>
@@ -401,13 +401,13 @@ liftCond (clause is [ante,conseq]) ==
 formatPred u ==
          --Assumes that $e is set up to point to an environment
   u is ["has",a,b] =>
-    atom b and isCategoryForm([b],$e) => ["has",a,[b]]
-    atom b => ["has",a,["ATTRIBUTE",b]]
+    b isnt [.,:.] and isCategoryForm([b],$e) => ["has",a,[b]]
+    b isnt [.,:.] => ["has",a,["ATTRIBUTE",b]]
     isCategoryForm(b,$e) => u
     b is ["ATTRIBUTE",.] => u
     b is ["SIGNATURE",:.] => u
     ["has",a,["ATTRIBUTE",b]]
-  atom u => u
+  u isnt [.,:.] => u
   u is ["and",:v] => ["and",:[formatPred w for w in v]]
   systemError ['"formatPred",u]
  
diff --git a/src/interp/msgdb.boot b/src/interp/msgdb.boot
index 6abdf340..c0da49b3 100644
--- a/src/interp/msgdb.boot
+++ b/src/interp/msgdb.boot
@@ -119,7 +119,7 @@ getKeyedMsg key == fetchKeyedMsg(key,false)
 segmentKeyedMsg(msg) == string2Words msg
 
 segmentedMsgPreprocess x ==
-  atom x => x
+  x isnt [.,:.] => x
   [head,:tail] := x
   center := rightJust := nil
   if member(head, '(%ceon "%ceon")) then center := true
@@ -238,7 +238,7 @@ substituteSegmentedMsg(msg,args) ==
 
 addBlanks msg ==
   -- adds proper blanks
-  atom msg => msg
+  msg isnt [.,:.] => msg
   null msg => msg
   # msg = 1 => msg
   blanksOff := false
@@ -292,7 +292,7 @@ noBlankAfterP word==
 cleanUpSegmentedMsg msg ==
   -- removes any junk like double blanks
   -- takes a reversed msg and puts it in the correct order
-  atom msg => msg
+  msg isnt [.,:.] => msg
   blanks := ['" "," "]
   haveBlank := nil
   prims :=
@@ -531,7 +531,7 @@ throwKeyedMsgCannotCoerceWithValue(val,t1,t2) ==
 --% Some Standard Message Printing Functions
 
 bright x == ['"%b",:(cons?(x) and null rest lastNode x => x; [x]),'"%d"]
---bright x == ['"%b",:(atom x => [x]; x),'"%d"]
+--bright x == ['"%b",:(x isnt [.,:.] => [x]; x),'"%d"]
 
 mkMessage msg ==
   msg and (cons? msg) and member((first msg),'(%l "%l"))  and
@@ -716,7 +716,7 @@ tabber num ==
 brightPrintCenter(x,out == $OutputStream) ==
   $texFormatting => brightPrintCenterAsTeX(x,out)
   -- centers rst within $LINELENGTH, checking for %l's
-  atom x =>
+  x isnt [.,:.] =>
     x := object2String x
     wid := # x
     if wid < $LINELENGTH then
@@ -742,7 +742,7 @@ brightPrintCenter(x,out == $OutputStream) ==
   nil
 
 brightPrintCenterAsTeX(x, out == $OutputStream) ==
-  atom x =>
+  x isnt [.,:.] =>
     sayString('"\centerline{",out)
     sayString(x,out)
     sayString('"}",out)
@@ -762,7 +762,7 @@ brightPrintCenterAsTeX(x, out == $OutputStream) ==
 
 brightPrintRightJustify(x, out == $OutputStream) ==
   -- right justifies rst within $LINELENGTH, checking for %l's
-  atom x =>
+  x isnt [.,:.] =>
     x := object2String x
     wid := # x
     wid < $LINELENGTH =>
@@ -791,7 +791,7 @@ brightPrintRightJustify(x, out == $OutputStream) ==
 
 sayBrightlyLength l ==
   null l => 0
-  atom l => sayBrightlyLength1 l
+  l isnt [.,:.] => sayBrightlyLength1 l
   sayBrightlyLength1 first l + sayBrightlyLength rest l
 
 sayBrightlyLength1 x ==
@@ -806,7 +806,7 @@ sayBrightlyLength1 x ==
   -- following line helps find certain bugs that slip through
   -- also see brightPrintHighlight
   vector? x => # '"UNPRINTABLE"
-  atom x => # toString x
+  x isnt [.,:.] => # toString x
   2 + sayBrightlyLength x
 
 sayAsManyPerLineAsPossible l ==
@@ -883,7 +883,7 @@ sayDisplayWidth x ==
   # atom2String x
 
 sayWidth x ==
-  atom x => # atom2String x
+  x isnt [.,:.] => # atom2String x
   +/[fn y for y in x] where fn y ==
     sayWidth y
 
@@ -950,7 +950,7 @@ splitSayBrightly u ==
   u
 
 splitSayBrightlyArgument u ==
-  atom u => nil
+  u isnt [.,:.] => nil
   while splitListSayBrightly u is [head,:u] repeat result:= [head,:result]
   result => [:reverse! result,u]
   [u]
diff --git a/src/interp/newfort.boot b/src/interp/newfort.boot
index b536b201..7edba7aa 100644
--- a/src/interp/newfort.boot
+++ b/src/interp/newfort.boot
@@ -100,7 +100,7 @@ exp2Fort1 l ==
  
 exp2Fort2(e,prec,oldOp) ==
   null e    => nil
-  atom e    => [object2String e]
+  e isnt [.,:.] => [object2String e]
   e is [ "=",lhs,rhs] or e is [ '"=",lhs,rhs] =>
     ['"%l",:exp2Fort2(rhs,prec,'"="),'"=",:exp2Fort2(lhs,prec,'"=")]
  
@@ -120,7 +120,7 @@ exp2Fort2(e,prec,oldOp) ==
     (p := position(op,unaryOps)) > -1 =>
       nprec := unaryPrecs.p
       s := [:exp2Fort2(first args,nprec,op),op]
-      op = '"-" and atom first args => s
+      op = '"-" and first args isnt [.,:.] => s
       op = oldOp and member(op,['"*",'"+"]) => s
       nprec <= prec => ['")",:s,'"("]
       s
@@ -167,7 +167,7 @@ exp2FortOptimize e ==
   --   1         extract common subexpressions
   --   2         try to optimize computing of powers
   $exprStack : local := nil
-  atom e => [e]
+  e isnt [.,:.] => [e]
   $fortranOptimizationLevel = 0 =>
     e1 := exp2FortOptimizeArray e
     reverse! [e1,:$exprStack]
@@ -214,8 +214,8 @@ beenHere(e,n) ==
 
 exp2FortOptimizeCS1 e ==
   -- we do nothing with atoms or simple lists containing atoms
-  atom(e) or (atom first e and null rest e) => e
-  e is [op,arg] and object2Identifier op = "-" and atom arg => e
+  e isnt [.,:.] or (first e isnt [.,:.] and null rest e) => e
+  e is [op,arg] and object2Identifier op = "-" and arg isnt [.,:.] => e
 
   -- see if we have been here before
   not (object2Identifier first e in '(ROW AGGLST)) and
@@ -233,7 +233,7 @@ exp2FortOptimizeCS1 e ==
       $fortCsExprStack := rest $fortCsExprStack
     g := rest f
     -- check to see of we have an non-nil atomic CDR
-    g and atom g =>
+    g and g isnt [.,:.] =>
       pushCsStacks(f,'CDR)
       f.rest := exp2FortOptimizeCS1 g
       popCsStacks(0)
@@ -254,7 +254,7 @@ exp2FortOptimizeCS1 e ==
  
 exp2FortOptimizeArray e ==
   -- this handles arrays
-  atom e => e
+  e isnt [.,:.] => e
   [op,:args] := e
   op1 := object2Identifier op
   op1 in '(BRACE BRACKET) =>
@@ -371,7 +371,7 @@ formatAsFortranExpression x ==
 
  
 dispfortexp x ==
-  if atom(x) or x is [op,:.] and
+  if x isnt [.,:.] or x is [op,:.] and
     not (object2Identifier op in '(_= MATRIX construct ))
   then
       var := makeSymbol strconc('"R",object2String $IOindex)
@@ -438,7 +438,7 @@ exp2FortSpecial(op,args,nargs) ==
   --the next line is NEVER used by FORTRAN code but is needed when
   --  called to get a linearized form for the browser
   op = "QUOTE" =>
-    atom (arg := first args) => STRINGIMAGE arg
+    (arg := first args) isnt [.,:.] => STRINGIMAGE arg
     tailPart := strconc/[strconc('",",x) for x in rest arg]
     strconc('"[",first arg,tailPart,'"]")
   op = "PAREN" =>
@@ -670,7 +670,7 @@ checkType ty ==
 
 mkParameterList l ==
   [par2string(u) for u in l] where par2string u ==
-      atom(u) => STRINGIMAGE u
+      u isnt [.,:.] => STRINGIMAGE u
       u := rest second u
       apply(function strconc,[STRINGIMAGE(first u),'"(",_
                :rest [:['",",:statement2Fortran(v)] for v in rest u],'")"])
@@ -687,7 +687,7 @@ fortFormatTypes(typeName,names) ==
   typeName = '"CHARACTER" =>
     fortFormatCharacterTypes([unravel(u) for u in names])
       where unravel u ==
-              atom u => u
+              u isnt [.,:.] => u
               CDADR u
   fortFormatTypes1(typeName,mkParameterList names)
 
@@ -712,7 +712,7 @@ fortFormatCharacterTypes(names) ==
   sortedByLength := []
   genuineArrays  := []
   for u in names repeat
-    atom u => sortedByLength := insertEntry(0,u,sortedByLength)
+    u isnt [.,:.] => sortedByLength := insertEntry(0,u,sortedByLength)
     #u=2 => sortedByLength := insertEntry(second u,first u,sortedByLength)
     genuineArrays := [u,:genuineArrays]
   for u in sortedByLength repeat
@@ -797,7 +797,7 @@ fortPre1 e ==
   member(e, imags) => ['"CMPLX",fortPre1(0),fortPre1(1)]
   -- other special objects
   STRINGIMAGE(e).0 = char "%" => subSequence(STRINGIMAGE e,1)
-  atom e => e
+  e isnt [.,:.] => e
   [op, :args] := e
   member(op,["**" , '"**"]) =>
     [rand,exponent] := args
@@ -888,7 +888,7 @@ fortExpSize e ==
   -- This function overestimates the size because it assumes that e.g.
   -- (+ x (+ y z)) will be printed as "x+(y+z)" rather than "x+y+z"
   -- which is the actual case.
-  atom e => # STRINGIMAGE e
+  e isnt [.,:.] => # STRINGIMAGE e
   #e > 3 => 2+fortSize [fortExpSize x for x in e]
   #e < 3 => 2+fortSize [fortExpSize x for x in e]
   [op,arg1,arg2] := e
@@ -906,7 +906,7 @@ fortExpSize e ==
 fortSize e ==
   +/[elen u for u in e] where
     elen z ==
-      atom z => z
+      z isnt [.,:.] => z
       first z
  
 tempLen () == 1 + # STRINGIMAGE $exp2FortTempVarIndex
@@ -950,7 +950,7 @@ segment1(e,maxSize) ==
  
 segment2(e,topSize) ==
   maxSize := $maximumFortranExpressionLength -tempLen()-1
-  atom(e) => [e]
+  e isnt [.,:.] => [e]
   exprs := nil
   newE  := [first e]
   topSize := topSize - fortExpSize newE
diff --git a/src/interp/nruncomp.boot b/src/interp/nruncomp.boot
index f3ee3e09..719476a4 100644
--- a/src/interp/nruncomp.boot
+++ b/src/interp/nruncomp.boot
@@ -143,7 +143,7 @@ listOfBoundVars form ==
     u:=u.expr
     builtinConstructor? KAR u => listOfBoundVars u
     [form]
-  atom form => []
+  form isnt [.,:.] => []
   first form is 'QUOTE => []
   -- We don't want to pick up the tag, only the domain
   first form = ":" => listOfBoundVars third form
@@ -165,12 +165,12 @@ optDeltaEntry(op,sig,dc,eltOrConst) ==
   -- stage of the compilation process.
   dc is '$ => nil
   ndc :=
-    atom dc and (dcval := get(dc,'value,$e)) => dcval.expr
+    dc isnt [.,:.] and (dcval := get(dc,'value,$e)) => dcval.expr
     dc
   sig := MSUBST(ndc,dc,sig)
   -- Don't bother if the domain of computation is not an instantiation
   -- nor a candidate for inlining.
-  atom ndc or not optimizableDomain? ndc => nil
+  ndc isnt [.,:.] or not optimizableDomain? ndc => nil
   fun := lookupDefiningFunction(op,sig,ndc)
   -- following code is to handle selectors like first, rest
   if fun = nil and needToQuoteFlags?(sig,$e) then
@@ -198,7 +198,7 @@ genDeltaEntry(opMmPair,e) ==
   if $profileCompiler then profileRecord(dc,op,sig)
   eltOrConst is 'XLAM => cform
   if eltOrConst is 'Subsumed then eltOrConst := 'ELT
-  if atom dc then
+  if dc isnt [.,:.] then
     dc = "$" => nsig := sig
     if integer? nsig then nsig := MSUBST("$",dc,substitute("$$","$",sig))
   setDifference(listOfBoundVars dc,$functorLocalParameters) ~= [] =>
@@ -246,7 +246,7 @@ NRTgetLocalIndex item ==
   k := NRTassocIndex item => k
   item = "$" => 0
   item = "$$" => 2
-  atom item and not symbolMember?(item,$formalArgList) =>  --give slots to atoms
+  item isnt [.,:.] and not symbolMember?(item,$formalArgList) =>  --give slots to atoms
     $NRTdeltaList:= [["%domain",NRTaddInner item],:$NRTdeltaList]
     $NRTdeltaListComp:=[item,:$NRTdeltaListComp]
     index := $NRTbase + $NRTdeltaLength      -- slot number to return
@@ -289,7 +289,7 @@ NRTassignCapsuleFunctionSlot(op,sig) ==
 ++ NRTaddInner should call following function instead of NRTgetLocalIndex
 ++ This would prevent putting spurious items in $NRTdeltaList
 NRTinnerGetLocalIndex x ==
-  atom x => x
+  x isnt [.,:.] => x
   op := x.op
   ident? op and (constructor? op or builtinConstructor? op) =>
     NRTgetLocalIndex x
@@ -300,7 +300,7 @@ NRTinnerGetLocalIndex x ==
 NRTaddInner x ==
 --called by genDeltaEntry and others that affect $NRTdeltaList
   do
-    atom x => nil
+    x isnt [.,:.] => nil
     x is [":",y,z] => [x.op,y,NRTinnerGetLocalIndex z]
     x is ['SubDomain,y,:.] => NRTinnerGetLocalIndex y
     builtinConstructor? x.op or x.op is "[||]" =>
@@ -402,7 +402,7 @@ washFunctorBody form == main form where
 --=======================================================================
 stuffSlot(dollar,i,item) ==
   vectorRef(dollar,i) :=
-    atom item => [symbolFunction item,:dollar]
+    item isnt [.,:.] => [symbolFunction item,:dollar]
     item is [n,:op] and integer? n => ['newGoGet,dollar,:item]
     item is ['CONS,.,['FUNCALL,a,b]] =>
       b is '$ => ['makeSpadConstant,eval a,dollar,i]
@@ -571,8 +571,8 @@ NRTcheckVector domainShell ==
     v := vectorRef(domainShell,i)
     v=true => nil  --item is marked; ignore
     v=nil => nil
-    atom v => systemErrorHere '"CheckVector"
-    atom first v => nil  --category form; ignore
+    v isnt [.,:.] => systemErrorHere '"CheckVector"
+    first v isnt [.,:.] => nil  --category form; ignore
     assoc(first v,alist) => nil
     alist := [[first v,:vectorRef($SetFunctions,i)],:alist]
   alist
@@ -714,7 +714,7 @@ vectorLocation(op,sig) ==
 NRTsubstDelta(initSig) ==
   sig := [replaceSlotTypes s for s in initSig] where
      replaceSlotTypes(t) ==
-        atom t =>
+        t isnt [.,:.] =>
           not integer? t => t
           t = 0 => '$
           t = 2 => '_$_$
@@ -735,7 +735,7 @@ NRTputInLocalReferences bod ==
   NRTputInHead bod
 
 NRTputInHead bod ==
-  atom bod => bod
+  bod isnt [.,:.] => bod
   bod is ['SPADCALL,:args,fn] =>
     NRTputInTail rest bod --NOTE: args = COPY of rest bod
     -- The following test allows function-returning expressions
@@ -755,10 +755,10 @@ NRTputInHead bod ==
 
 NRTputInTail x ==
   for y in tails x repeat
-    atom (u := first y) =>
+    (u := first y) isnt [.,:.] =>
       u='$ or LASSOC(u,$devaluateList) => nil
       k:= NRTassocIndex u =>
-        atom u => y.first := ['%vref,'_$,k]
+        u isnt [.,:.] => y.first := ['%vref,'_$,k]
         -- u atomic means that the slot will always contain a vector
         y.first := ['SPADCHECKELT,'_$,k]
       --this reference must check that slot is a vector
diff --git a/src/interp/nrunfast.boot b/src/interp/nrunfast.boot
index 4b1d036f..3424ecf1 100644
--- a/src/interp/nrunfast.boot
+++ b/src/interp/nrunfast.boot
@@ -450,7 +450,7 @@ lazyMatchArg2(s,a,dollar,domain,typeFlag) ==
     string? s => a = s
     s is ['QUOTE,y] and PNAME y = a
     ident? s and symbolName s = a
-  atom a =>  a = s
+  a isnt [.,:.] =>  a = s
   op := opOf a
   op is 'NRTEVAL => s = nrtEval(second a,domain)
   op is 'QUOTE => s = second a
@@ -499,13 +499,13 @@ lazyMatchArgDollarCheck(s,d,dollarName,domainName) ==
     x is ['elt,someDomain,opname] => lookupInDomainByName(opname,evalDomain someDomain,arg)
     x is '$ and (arg = dollarName or arg = domainName) => true
     x = dollarName and arg = domainName => true
-    atom x or atom arg => false
+    x isnt [.,:.] or arg isnt [.,:.] => false
     xt and first x = first arg =>
       lazyMatchArgDollarCheck(x,arg,dollarName,domainName)
     false
 
 lookupInDomainByName(op,domain,arg) ==
-  atom arg => nil
+  arg isnt [.,:.] => nil
   opvec := domainRef(domain,1) . 2
   numvec := getDomainByteVector domain
   predvec := domainPredicates domain
@@ -543,7 +543,7 @@ newExpandTypeSlot(slot, dollar, domain) ==
  
 newExpandLocalType(lazyt,dollar,domain) ==
   vector? lazyt => canonicalForm lazyt
-  atom lazyt => lazyt
+  lazyt isnt [.,:.] => lazyt
   lazyt is [vec,.,:lazyForm] and vector? vec =>              --old style
     newExpandLocalTypeForm(lazyForm,dollar,domain)
   newExpandLocalTypeForm(lazyt,dollar,domain)             --new style
@@ -569,7 +569,7 @@ newExpandLocalTypeArgs(u,dollar,domain,typeFlag) ==
   u is ['NRTEVAL,y] => nrtEval(y,domain)
   u is ['QUOTE,y] => y
   u is "$$" => canonicalForm domain
-  atom u => u   --can be first, rest, etc.
+  u isnt [.,:.] => u   --can be first, rest, etc.
   newExpandLocalTypeForm(u,dollar,domain)
  
 nrtEval(expr,dom) ==
@@ -610,7 +610,7 @@ lazyDomainSet(lazyForm,thisDomain,slot) ==
 ++ such resolution has already occured.
 resolveNiladicConstructors form ==
   ident? form and niladicConstructorFromDB form => [form]
-  atom form => form
+  form isnt [.,:.] => form
   form is ["QUOTE",:.] => form
   for args in tails rest form repeat
     args.first := resolveNiladicConstructors first args
@@ -629,7 +629,7 @@ newHasTest(domform,catOrAtt) ==
   cons? domform and builtinFunctorName? domform.op =>
     ofCategory(domform,catOrAtt)
   op := opOf catOrAtt
-  isAtom := atom catOrAtt
+  isAtom := catOrAtt isnt [.,:.]
   not isAtom and op is 'Join =>
     and/[newHasTest(domform,x) for x in rest catOrAtt]
 -- we will refuse to say yes for 'Cat has Cat'
@@ -640,7 +640,7 @@ newHasTest(domform,catOrAtt) ==
       for [aCat,:cond] in [:ancestorsOf(domform,nil),:applySubst(pairList($FormalMapVariableList,rest domform),getConstructorAttributesFromDB(opOf domform))] |  aCat = catOrAtt  repeat
          return evalCond cond where
            evalCond x ==
-             atom x => x
+             x isnt [.,:.] => x
              [pred,:l] := x
              pred = "has" => 
                   l is [ w1,['ATTRIBUTE,w2]] => newHasTest(w1,w2) 
@@ -682,7 +682,7 @@ lazyMatchAssocV1(x,vec,domain) ==               --old style slot4
 sayLooking(prefix,op,sig,dom) ==
   $monitorNewWorld := false
   dollar := devaluate dom
-  atom dollar or vector? dollar or "or"/[vector? x for x in dollar] => systemError nil
+  dollar isnt [.,:.] or vector? dollar or "or"/[vector? x for x in dollar] => systemError nil
   sayBrightly
     concat(prefix,formatOpSignature(op,sig),bright '"from ",form2String dollar)
   $monitorNewWorld := true
diff --git a/src/interp/parse.boot b/src/interp/parse.boot
index 6ab39d19..f7db82fe 100644
--- a/src/interp/parse.boot
+++ b/src/interp/parse.boot
@@ -69,7 +69,7 @@ parseTransform x ==
 
 parseTran: %ParseForm -> %Form
 parseTran x ==
-  atom x => x
+  x isnt [.,:.] => x
   [op,:argl]:= x
   u := g(op) where g op == (op is ["elt",op,x] => g x; op)
   u="construct" =>
@@ -89,7 +89,7 @@ parseTypeList l ==
 
 parseTranList: %List %Form -> %List %Form
 parseTranList l ==
-  atom l => parseTran l
+  l isnt [.,:.] => parseTran l
   [parseTran first l,:parseTranList rest l]
  
 parseConstruct: %ParseForm -> %Form
@@ -129,13 +129,13 @@ transIs1 u ==
     h:= [":",transIs x]
     (v:= transIs1 y) is [":",z] => [h,z]
     v="nil" => second h
-    atom v => [h,[":",v]]
+    v isnt [.,:.] => [h,[":",v]]
     [h,:v]
   u is ["cons",x,y] =>
     h:= transIs x
     (v:= transIs1 y) is [":",z] => [h,z]
     v="nil" => [h]
-    atom v => [h,[":",v]]
+    v isnt [.,:.] => [h,[":",v]]
     [h,:v]
   u
  
@@ -167,12 +167,12 @@ parseBigelt t ==
 
 transUnCons: %ParseForm -> %Form 
 transUnCons u ==
-  atom u => systemErrorHere ["transUnCons",u]
+  u isnt [.,:.] => systemErrorHere ["transUnCons",u]
   u is ["APPEND",x,y] =>
     y = nil => x
     systemErrorHere ["transUnCons",u]
   u is ["CONS",x,y] =>
-    atom y => [x,:y]
+    y isnt [.,:.] => [x,:y]
     [x,:transUnCons y]
 
 parseCoerce: %ParseForm -> %Form 
@@ -216,8 +216,8 @@ parseDEF t ==
  
 parseLhs: %ParseForm -> %Form
 parseLhs x ==
-  atom x => parseTran x
-  atom first x => [parseTran first x,:[transIs parseTran y for y in rest x]]
+  x isnt [.,:.] => parseTran x
+  first x isnt [.,:.] => [parseTran first x,:[transIs parseTran y for y in rest x]]
   parseTran x
  
 
@@ -395,7 +395,7 @@ transCategoryItem x ==
   x is ["SIGNATURE",lhs,rhs] =>
     lhs is ["LISTOF",:y] =>
       "append" /[transCategoryItem ["SIGNATURE",z,rhs] for z in y]
-    atom lhs =>
+    lhs isnt [.,:.] =>
       lhs := washOperatorName lhs
       rhs is ["Mapping",:m] =>
         m is [.,"constant"] => [["SIGNATURE",lhs,[first m],"constant"]]
diff --git a/src/interp/pathname.boot b/src/interp/pathname.boot
index e5c9c8f3..97cab246 100644
--- a/src/interp/pathname.boot
+++ b/src/interp/pathname.boot
@@ -49,7 +49,7 @@ pathname? p ==
  
 pathname p ==
   pathname? p => p
-  atom p => PATHNAME p
+  p isnt [.,:.] => PATHNAME p
   if #p>2 then p:=[p.0,p.1]
   PATHNAME apply(FUNCTION MAKE_-FILENAME, p)
  
diff --git a/src/interp/pf2atree.boot b/src/interp/pf2atree.boot
index 584244f8..eaf188a8 100644
--- a/src/interp/pf2atree.boot
+++ b/src/interp/pf2atree.boot
@@ -524,7 +524,7 @@ pfCollect2Atree pf ==
 --
 --  patternVarsOf1(expr, varList) ==
 --    null expr => varList
---    atom expr =>
+--    expr isnt [.,:.] =>
 --      not symbol? expr => varList
 --      SymMemQ(expr, varList) => varList
 --      [expr, :varList]
diff --git a/src/interp/pf2sex.boot b/src/interp/pf2sex.boot
index b531026b..30e619ff 100644
--- a/src/interp/pf2sex.boot
+++ b/src/interp/pf2sex.boot
@@ -473,7 +473,7 @@ patternVarsOf expr ==
 
 patternVarsOf1(expr, varList) ==
   null expr => varList
-  atom expr =>
+  expr isnt [.,:.] =>
     not symbol? expr => varList
     SymMemQ(expr, varList) => varList
     [expr, :varList]
diff --git a/src/interp/posit.boot b/src/interp/posit.boot
index 82d1f09d..9e3af606 100644
--- a/src/interp/posit.boot
+++ b/src/interp/posit.boot
@@ -86,7 +86,7 @@ lnFileName lineObject    ==
     ncBug('"there is no file name in %1", [lineObject] )
  
 lnFileName? lineObject   ==
-    atom (fN := lineObject.4)  => nil
+    (fN := lineObject.4) isnt [.,:.]  => nil
     fN
  
 lnPlaceOfOrigin lineObject ==
diff --git a/src/interp/postpar.boot b/src/interp/postpar.boot
index 7f18be08..eaaa254d 100644
--- a/src/interp/postpar.boot
+++ b/src/interp/postpar.boot
@@ -80,7 +80,7 @@ displayPreCompilationErrors() ==
 
 postTran: %ParseTree -> %ParseForm
 postTran x ==
-  atom x =>
+  x isnt [.,:.] =>
     postAtom x
   op := first x
   symbol? op and (f:= property(op,'postTran)) => FUNCALL(f,x)
@@ -228,16 +228,16 @@ postDef t ==
   [form,targetType]:=
     lhs is [":",:.] => rest lhs
     [lhs,nil]
-  if not $InteractiveMode and atom form then form := [form]
+  if not $InteractiveMode and form isnt [.,:.] then form := [form]
   newLhs:=
-    atom form => form
+    form isnt [.,:.] => form
     [op,:argl]:= [(x is [":",a,.] => a; x) for x in form]
     [op,:postDefArgs argl]
   argTypeList:=
-    atom form => nil
+    form isnt [.,:.] => nil
     [(x is [":",.,t] => t; nil) for x in rest form]
   typeList:= [targetType,:argTypeList]
-  if atom form then form := [form]
+  if form isnt [.,:.] then form := [form]
   specialCaseForm := [nil for x in form]
   ["DEF",newLhs,typeList,specialCaseForm,postTran rhs]
 
@@ -247,7 +247,7 @@ postDefArgs argl ==
   argl is [[":",a],:b] =>
     b ~= nil => postError
       ['"   Argument",:bright a,'"of indefinite length must be last"]
-    atom a or a is ["QUOTE",:.] => a
+    a isnt [.,:.] or a is ["QUOTE",:.] => a
     postError
       ['"   Argument",:bright a,'"of indefinite length must be a name"]
   [first argl,:postDefArgs rest argl]
@@ -264,7 +264,7 @@ postMDef(t) ==
     lhs is [":",:.] => rest lhs
     [lhs,nil]
   form:=
-    atom form => [form]
+    form isnt [.,:.] => [form]
     form
   newLhs:= [(x is [":",a,:.] => a; x) for x in form]
   typeList:= [targetType,:[(x is [":",.,t] => t; nil) for x in rest form]]
@@ -293,7 +293,7 @@ postForm: %ParseTree -> %ParseForm
 postForm u ==
   u isnt [op,:argl] => systemErrorHere ["postForm",u]
   x:=
-    atom op =>
+    op isnt [.,:.] =>
       argl':= postTranList argl
       op':=
         true=> op
@@ -495,7 +495,7 @@ postSignature t ==
 
 killColons: %ParseTree -> %ParseForm
 killColons x ==
-  atom x => x
+  x isnt [.,:.] => x
   x is [op,:.] and op in '(Record Union %Forall %Exist) => x
   x is [":",.,y] => killColons y
   [killColons first x,:killColons rest x]
@@ -551,7 +551,7 @@ postTransformCheck x ==
 
 postcheck: %ParseTree -> %ParseForm
 postcheck x ==
-  atom x => nil
+  x isnt [.,:.] => nil
   x is ["DEF",form,[target,:.],:.] =>
     setDefOp form
     postcheck rest rest x
@@ -562,7 +562,7 @@ postcheck x ==
 setDefOp: %ParseForm -> %Thing
 setDefOp f ==
   if f is [":",g,:.] then f := g
-  f := (atom f => f; first f)
+  f := (f isnt [.,:.] => f; first f)
   if $topOp then $defOp:= f else $topOp:= f
 
 unComma: %ParseForm -> %ParseForm
diff --git a/src/interp/showimp.boot b/src/interp/showimp.boot
index ae6c65ad..347a09a1 100644
--- a/src/interp/showimp.boot
+++ b/src/interp/showimp.boot
@@ -246,8 +246,8 @@ formatLazyDomain(dom,x) ==
 formatLazyDomainForm(dom,x) ==
   x = 0 => ["$"]
   integer? x => formatLazyDomain(dom,dom.x)
-  atom x => x
-  x is ['NRTEVAL,y] => (atom y => [y]; y)
+  x isnt [.,:.] => x
+  x is ['NRTEVAL,y] => (y isnt [.,:.] => [y]; y)
   [first x,:[formatLazyDomainForm(dom,y) for y in rest x]]
  
 
@@ -282,7 +282,7 @@ dcSlots con ==
     item := template.i
     item is [n,:op] and integer? n => dcOpLatchPrint(op,n)
     null item and i > 5 => sayBrightly ['"arg  ",strconc('"#",STRINGIMAGE(i - 5))]
-    atom item => sayBrightly ['"fun  ",item]
+    item isnt [.,:.] => sayBrightly ['"fun  ",item]
     item is ['CONS,.,['FUNCALL,[.,a],b]] => sayBrightly ['"constant ",a]
     sayBrightly concat('"lazy ",form2String formatSlotDomain i)
  
@@ -321,8 +321,8 @@ formatSlotDomain x ==
     val := $infovec.0.x
     null val => [strconc('"#",STRINGIMAGE (x  - 5))]
     formatSlotDomain val
-  atom x => x
-  x is ['NRTEVAL,y] => (atom y => [y]; y)
+  x isnt [.,:.] => x
+  x is ['NRTEVAL,y] => (y isnt [.,:.] => [y]; y)
   [first x,:[formatSlotDomain y for y in rest x]]
  
 --=======================================================================
@@ -363,7 +363,7 @@ dcOpPrint(op,index) ==
     slotNumber = 0 => '"subsumed by next entry"
     slotNumber = 1 => '"missing"
     name := $infovec.0.slotNumber
-    atom name => name
+    name isnt [.,:.] => name
     name is ["CONS","IDENTITY",
               ["FUNCALL", ["dispatchFunction", impl],"$"]] =>
       kind := 'CONST
@@ -471,7 +471,7 @@ dcSize(:options) ==
   fun   := 0  --# of function slots
   lazyNodes := 0 --# of nodes needed for lazy domain slots
   for i in 5..maxindex repeat
-    atom (item := template.i) =>   fun := fun + 1
+    (item := template.i) isnt [.,:.] =>   fun := fun + 1
     integer? first item    => latch := latch + 1
     'T                 =>  
        lazy := lazy + 1
@@ -537,7 +537,7 @@ halfWordSize(n) ==
   2 * n
 
 numberOfNodes(x) ==
-  atom x => 0
+  x isnt [.,:.] => 0
   1 + numberOfNodes first x + numberOfNodes rest x
 
 template con ==
@@ -596,7 +596,7 @@ dcOps conname ==
   for [op,:u] in reverse getConstructorOperationsFromDB conname repeat
     for [sig,slot,pred,key,:.] in u repeat
       suffix := 
-        atom pred => nil
+        pred isnt [.,:.] => nil
         concat('" if ",pred2English pred)
       key is 'Subsumed =>
         sayBrightly [:formatOpSignature(op,sig),'" subsumed by ",:formatOpSignature(op,slot),:suffix]
diff --git a/src/interp/simpbool.boot b/src/interp/simpbool.boot
index 9c088079..c14c8d5e 100644
--- a/src/interp/simpbool.boot
+++ b/src/interp/simpbool.boot
@@ -38,7 +38,7 @@ simpBool x == dnf2pf reduceDnf be x
  
 reduceDnf u ==
 -- (OR (AND ..b..) b) ==> (OR  b  )
-  atom u => u
+  u isnt [.,:.] => u
   for x in u repeat
     ok := true
     for y in u repeat
@@ -78,14 +78,14 @@ andReduce(x,y) ==
 dnf2pf(x) ==
   x = 'true => 'T
   x = 'false => nil
-  atom x => x
+  x isnt [.,:.] => x
   mkpf(
     [mkpf([:[k for k in b],:[['not,k] for k in a]],'AND) for [a,b] in x],'OR)
 be x == b2dnf x
 b2dnf x ==
   x = 'T => 'true
   x = nil => 'false
-  atom x => bassert x
+  x isnt [.,:.] => bassert x
   [op,:argl] := x
   op in '(AND and) => band argl
   op in '(OR or)   => bor argl
diff --git a/src/interp/slam.boot b/src/interp/slam.boot
index f10c3c17..f069dfb1 100644
--- a/src/interp/slam.boot
+++ b/src/interp/slam.boot
@@ -124,7 +124,7 @@ mkDiffAssoc(op,body,k,sharpPosition,sharpArg,diffSlot,vecname) ==
   -- form substitution list of the form:
   -- ( ((f (,DIFFERENCE #1 1)) . #2) ((f (,DIFFERENCE #1 2)) . #3) ...)
   --   but also checking that all difference values lie in 1..k
-  atom body => nil
+  body isnt [.,:.] => nil
   body is ['%when,:pl] =>
     "union"/[mkDiffAssoc(op,c,k,sharpPosition,sharpArg,diffSlot,vecname) for [p,c] in pl]
   body is [fn,:argl] =>
@@ -365,7 +365,7 @@ mkCacheVec(op,nam,kind,resetCode,countCode) ==
 --
 -- op2String op ==
 --   u:= linearFormatName op
---   atom u => PNAME u
+--   u isnt [.,:.] => PNAME u
 --   strconc/u
 --
 -- reportCacheStorePrint(op,kind,count) ==
diff --git a/src/interp/sys-utility.boot b/src/interp/sys-utility.boot
index b6c0ba0e..1b404d9b 100644
--- a/src/interp/sys-utility.boot
+++ b/src/interp/sys-utility.boot
@@ -120,28 +120,28 @@ CONTAINED(x,y) == main where
     cons? y => eq(x, first y) or eq(x, rest y)
     symbolEq?(x,y)
   equal(x,y) ==
-    atom y => x = y
+    y isnt [.,:.] => x = y
     equal(x, first y) or equal(x, rest y)
 
 ++ Returns all the keys of association list `x'
 -- ??? Should not this be named `alistAllKeys'?
 ASSOCLEFT: %Thing -> %Thing
 ASSOCLEFT x ==
-  atom x => x
+  x isnt [.,:.] => x
   [first p for p in x]
 
 ++ Returns all the datums of association list `x'.
 -- ??? Should not this be named `alistAllValues'?
 ASSOCRIGHT: %Thing -> %Thing
 ASSOCRIGHT x ==
-  atom x => x
+  x isnt [.,:.] => x
   [rest p for p in x]
 
 ++ Put the association list pair `(x . y)' into `l', erasing any 
 ++ previous association for `x'.
 ADDASSOC: (%Thing,%Thing,%Alist(%Thing,%Thing)) -> %Alist(%Thing,%Thing)
 ADDASSOC(x,y,l) ==
-  atom l => [[x,:y],:l]
+  l isnt [.,:.] => [[x,:y],:l]
   x = first first l => [[x,:y],:rest l]
   [first l,:ADDASSOC(x,y,rest l)]
 
@@ -149,7 +149,7 @@ ADDASSOC(x,y,l) ==
 ++ Remove any assocation pair `(u . x)' from list `v'.
 DELLASOS: (%Thing,%Alist(%Thing,%Thing)) -> %Alist(%Thing,%Thing)
 DELLASOS(u,v) ==
-  atom v => nil
+  v isnt [.,:.] => nil
   u = first first v => rest v
   [first v,:DELLASOS(u,rest v)]
 
@@ -158,14 +158,14 @@ DELLASOS(u,v) ==
 -- ??? Should not this be named `alistValue'?
 LASSOC: (%Thing,%Alist(%Thing,%Thing)) -> %Thing
 LASSOC(x,y) ==
-  atom y => nil
+  y isnt [.,:.] => nil
   x = first first y => rest first y
   LASSOC(x,rest y)
 
 ++ Return the key associated with datum `x' in association list `y'.
 rassoc: (%Thing,%Alist(%Thing,%Thing)) -> %Thing
 rassoc(x,y) ==
-  atom y => nil
+  y isnt [.,:.] => nil
   x = rest first y => first first y
   rassoc(x,rest y)
 
diff --git a/src/interp/termrw.boot b/src/interp/termrw.boot
index 235bbd88..aa3283f2 100644
--- a/src/interp/termrw.boot
+++ b/src/interp/termrw.boot
@@ -45,7 +45,7 @@ termRW(t,R) ==
 termRW1(t,R) ==
   -- tries to do one reduction on the leftmost outermost subterm of t
   t0:= term1RW(t,R)
-  not sameObject?(t0,t) or atom t => t0
+  not sameObject?(t0,t) or t isnt [.,:.] => t0
   [t1,:t2]:= t
   tt1:= termRW1(t1,R)
   tt2:= t2 and termRW1(t2,R)
@@ -71,12 +71,12 @@ termMatch(tp,t,SL,vars) ==
   -- t is a term pattern, t a term
   -- then the result is the augmented substitution SL or 'failed
   tp=t => SL
-  atom tp =>
+  tp isnt [.,:.] =>
     symbolMember?(tp,vars) =>
       p:= ASSOC(tp,SL) => ( rest p=t )
       [[tp,:t],:SL]
     'failed
-  atom t => 'failed
+  t isnt [.,:.] => 'failed
   [tp1,:tp2]:= tp
   [t1,:t2]:= t
   SL:= termMatch(tp1,t1,SL,vars)
@@ -92,7 +92,7 @@ termMatch(tp,t,SL,vars) ==
 --   -- tests (by EQ), whether v occurs in term t
 --   -- v must not be nil
 --   sameObject?(v,t) => 'T
---   atom t => nil
+--   t isnt [.,:.] => nil
 --   isContained(v,first t) or isContained(v,rest t)
  
 augmentSub(v,t,SL) ==
@@ -125,7 +125,7 @@ subCopy0(t, SL) ==
 subCopyOrNil(t,SL) ==
   -- the same as subCopy, but the result is nil if nothing was copied
   p:= ASSOC(t,SL) => p
-  atom t => nil
+  t isnt [.,:.] => nil
   [t1,:t2]:= t
   t0:= subCopyOrNil(t1,SL) =>
     t2 => [t, :[rest t0,:subCopy0(t2,SL)]]
@@ -147,7 +147,7 @@ deepSubCopy0(t, SL) ==
 deepSubCopyOrNil(t,SL) ==
   -- the same as subCopy, but the result is nil if nothing was copied
   p:= ASSOC(t,SL) => [t,:deepSubCopy0(rest p, SL)]
-  atom t => nil
+  t isnt [.,:.] => nil
   [t1,:t2]:= t
   t0:= deepSubCopyOrNil(t1,SL) =>
     t2 => [t, :[rest t0,:deepSubCopy0(t2,SL)]]
diff --git a/src/interp/trace.boot b/src/interp/trace.boot
index 9465a19a..1d503bcf 100644
--- a/src/interp/trace.boot
+++ b/src/interp/trace.boot
@@ -90,9 +90,9 @@ trace1 l ==
       (lops := hasOption($options,'local)) =>
         null l => throwKeyedMsg("S2IT0019",nil)
         constructor := unabbrev
-          atom l => l
+          l isnt [.,:.] => l
           null rest l =>
-            atom first l => first l
+            first l isnt [.,:.] => first l
             first first l
           nil
         not(isFunctor constructor) => throwKeyedMsg("S2IT0020",nil)
@@ -207,7 +207,7 @@ getTraceOption (x is [key,:l]) ==
   key="of" =>
     ["of",:[hn y for y in l]] where
       hn x ==
-        atom x and not upperCase? STRINGIMAGE(x).0 =>
+        x isnt [.,:.] and not upperCase? STRINGIMAGE(x).0 =>
           isDomainOrPackage eval x => x
           stackTraceOptionError ["S2IT0013",[x]]
         g:= domainToGenvar x => g
@@ -299,7 +299,7 @@ untrace l ==
 
 transTraceItem x ==
   $doNotAddEmptyModeIfTrue: local:=true
-  atom x =>
+  x isnt [.,:.] =>
     (value:=get(x,"value",$InteractiveFrame)) and
       member(objMode value,$LangSupportTypes) =>
         x := objVal value
@@ -337,7 +337,7 @@ coerceSpadArgs2E(args) ==
         for arg in args for type in rest $tracedSpadModemap]
 
 subTypes(mm,sublist) ==
-  atom mm =>
+  mm isnt [.,:.] =>
     (s:= LASSOC(mm,sublist)) => s
     mm
   [subTypes(m,sublist) for m in mm]
@@ -451,7 +451,7 @@ spadTrace(domain,options) ==
          integer? n and
           isTraceable(triple:= [op,sig,n],domain)] where
             isTraceable(x is [.,.,n,:.],domain) ==
-              atom domain.n => nil
+              domain.n  isnt [.,:.] => nil
               functionSlot:= first domain.n
               GENSYMP functionSlot =>
                 (reportSpadTrace("Already Traced",x); nil)
@@ -650,7 +650,7 @@ getBpiNameIfTracedMap(name) ==
   name
 
 hasPair(key,l) ==
-  atom l => nil
+  l isnt [.,:.] => nil
   l is [[ =key,:a],:.] => a
   hasPair(key,rest l)
 
@@ -728,7 +728,7 @@ traceReply() ==
   sayBrightly '" "
   for x in _/TRACENAMES repeat
     x is [d,:.] and (isDomainOrPackage d) => addTraceItem d
-    atom x =>
+    x isnt [.,:.] =>
       isFunctor x => addTraceItem x
       (IS__GENVAR x =>
         addTraceItem eval x; functionList:= [x,:functionList])
@@ -745,19 +745,19 @@ traceReply() ==
   if $domains then
     displayList:= concat(prefix2String first $domains,
           [:concat('",",'" ",prefix2String x) for x in rest $domains])
-    if atom displayList then displayList:= [displayList]
+    if displayList isnt [.,:.] then displayList:= [displayList]
     sayBrightly '"   Domains traced: "
     sayBrightly flowSegmentedMsg(displayList,$LINELENGTH,6)
   if $packages then
     displayList:= concat(prefix2String first $packages,
           [:concat(", ",prefix2String x) for x in rest $packages])
-    if atom displayList then displayList:= [displayList]
+    if displayList isnt [.,:.] then displayList:= [displayList]
     sayBrightly '"   Packages traced: "
     sayBrightly flowSegmentedMsg(displayList,$LINELENGTH,6)
   if $constructors then
     displayList:= concat(abbreviate first $constructors,
           [:concat(", ",abbreviate x) for x in rest $constructors])
-    if atom displayList then displayList:= [displayList]
+    if displayList isnt [.,:.] then displayList:= [displayList]
     sayBrightly '"   Parameterized constructors traced:"
     sayBrightly flowSegmentedMsg(displayList,$LINELENGTH,6)
 
@@ -768,7 +768,7 @@ addTraceItem d ==
 
 _?t() ==
   null _/TRACENAMES => sayMSG bright '"nothing is traced"
-  for x in _/TRACENAMES | atom x and not IS__GENVAR x repeat
+  for x in _/TRACENAMES | x isnt [.,:.] and not IS__GENVAR x repeat
     if llm:= get(x,'localModemap,$InteractiveFrame) then
       x:= ([CADAR llm])
     sayMSG ['"Function",:bright rassocSub(x,$mapSubNameAlist),'"traced"]