==Icon and {{header|Unicon}}==
Icon and Unicon have special variables known as keywords. which Syntactically,are keywordssyntactically are preceded by an &.
<lang Unicon>
&allocated : integer* report memory use ▼
# &keyword # type returned(indicators) - brief description
&ascii : cset ASCII character set ▼
# indicators:
&clock : string time of day ▼
# * - generates multiple values ▼
&collections : integer* garbage collection activity ▼
# = - modifiable
&column : integer source code column ▼
# U - Unicon
&cset : cset universal character set
# G - Icon or Unicon with Graphics
¤t : co-expression current co-expression ▼
#
&date : string today's date
▲&allocated :# integer (* ) - report memory use
&dateline : string time stamp
&digitsascii : # cset digit- ASCII character charactersset
&dumpclock # : integer=string - time terminationof dumpday
▲&collections :# integer (* ) - garbage collection activity
&e : real - natural log e ▼
&errorcolumn :# integer=(U) - source fail oncode errorcolumn
▲& asciicset : # cset ASCII- universal character set
&errornumber : integer? - runtime error code ▼
▲¤t :# co-expression - current co-expression
&errortext : string? - runtime error message
▲& clockdate : # string time- oftoday's daydate
&errorvalue : any? - offending value ▼
&erroutdateline # : filestring - time standard error filestamp
&digits # cset - digit characters
&eventcode : integer= - program execution event ▼
&dump # integer(=) - termination dump
&eventsource : co-expression= - source of program execution events ▼
▲&e :# real - natural log e
&eventvalue : any= - program execution value ▼
&failerror # : noneinteger(=) - fail expressionon failureerror
▲&errornumber :# integer? - runtime error code
&features : string* - platform features ▼
&fileerrortext :# string? - runtime error current source filemessage
▲&errorvalue :# any? - offending value
&host : string - host machine name
&inputerrout :# file - standard inputerror file
▲&eventcode :# integer (= U) - program execution event
&lcase : cset - lowercase letters ▼
▲&eventsource :# co-expression (= U) - source of program execution events
&letters : cset - letters ▼
▲&eventvalue :# any (= U) - program execution value
&level : integer - call depth ▼
&linefail :# integernone - expression current source line numfailure
▲&features :# string* - platform features
&main : co-expression - main task ▼
&nowfile # : integerstring - current timesource file
&nullhost :# nullstring - host nullmachine valuename
&outputinput : # file - standard outputinput file
&philcase # : realcset - lowercase golden ratioletters
▲&letters :# cset - letters
&pos : integer= - string scanning position ▼
▲& columnlevel : # integer source- codecall columndepth
&progname : string= - program name
&randomline : # integer= - current randomsource numberline seednumber
®ionsmain : integer* # co-expression - regionmain sizestask
&now # integer(U) - current time
&source : co-expression invoking co-expression
&storagenull : integer* - memory# null - innull usevalue
&subjectoutput : string# file - stringstandard scanningoutput subjectfile
&syserrphi : integer - halt# onreal - systemgolden errorratio
&timepos : # integer(=) - elapsedstring scanning timeposition
&traceprogname # : integerstring(=) - traceprogram programname
&ucaserandom # : csetinteger(=) - upperrandom casenumber lettersseed
&versionregions :# stringinteger(*) - versionregion sizes
▲& mainsource :# co-expression - maininvoking taskco-expression
&storage # integer(*) - memory in use
▲* generates multiple values
▲& possubject # : integer=string - string scanning positionsubject
= modifiable
&syserr # integer - halt on system error
&time # integer(=) - elapsed time
▲& leveltrace :# integer (=) - trace call depthprogram
▲& lcaseucase :# cset - upper lowercasecase letters
&version # string - version</lang>
=={{header|J}}==
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