The following page contains reserved words. These are not part of the ANS Forth Standard. They are just proposed by various people and published here at FORTH.SF.NET for public review.

:NON: :STD:

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        ( c-addr u -- n )

Each call to this word shall return a different number. A system may use the string denoted by c-addr u when reporting an exception (if it is not caught). Many systems start with -256 and return consecutive decreasing numbers down to -4095.

 \ default implementation:
   VARIABLE NEXT-EXCEPTION  -1024 NEXT-EXCEPTION !
   : EXCEPTION ( c-addr u -- n )
      2DROP   NEXT-EXCEPTION @ DUP 1+ NEXT-EXCEPTION ! ;
   \ using a system link-list
   : EXCEPTION ( c-addr u -- n )
       EXCEPTION-LINK LINK, NEXT-EXCEPTION @ , STRING, ALIGN
       NEXT-EXCEPTION @ DUP 1+ NEXT-EXCEPTION ! ;
   \ example use
   s" Package Error" EXCEPTION VALUE PACKAGE-ERROR
   : ?THROW SWAP IF THROW THEN ;
   : when-run check-state PACKAGE-ERROR ?THROW ;

See: 9.6.1.2275 THROW, 9.6.1.0006 STRING,,