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
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.