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DCL Symbols and Verbs?

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The Question is:

 
We have many old DCL procedures that contain commands DELETEXX and SUBMITXX,
 which are used similarly to DELETE and SUBMIT commands.  We do not have any
 symbols defined, but these commands do seem to work similarly to their shorter
 versions (only differen
ce is that DELETEXX acts as if there was a SET NOON before the command so that
 the command procedure does not abort if the file is not found).  Is this a
 feature in DCL, or where else can I look to find out about these commands?  No
 one here seems to know
 where they came from.  Thanks.
 

The Answer is :

 
  The DCL verb syntax you are seeing is obscure and long-standing and
  expected (mis-)behaviour of DCL.  The use of this appended-character
  syntax is entirely and solely to avoid any existing symbols that might
  duplicate the verb; this syntax bypasses the symbol substitution that
  might otherwise occur.
 
  Use of SET SYMBOL is recommended over the appended-character syntax,
  though a defensive programmer might well choose to use SET :== SET
  or similar.
 
  Note that the DELETE command returns a warning status when the target
  file is not found, and a warning status is not of a sufficient severity
  level (by default; see the DCL command ON) to trigger the DCL command
  procedure to exit.
 
  In other words, the syntax is not connected to the SET NOON behaviour.
 

  

     

     
answer written or last revised on ( 7-MAY-2001 )
     
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