ABBREV in REXX

 ABBREV (Abbreviation)

+----------------------------------------------------------------------------+
|                                                                            |
| >>--ABBREV(information,info--.---------.--)----------------------------->< |
|                              '-,length-'                                   |
|                                                                            |
+----------------------------------------------------------------------------+

returns 1 if info is equal to the leading characters of information and the
length of info is not less than length. Returns 0 if either of these
conditions is not met.

If you specify length, it must be a positive whole number or zero.  The
default for length is the number of characters in info.

Here are some examples:

ABBREV('Print','Pri')      ->    1
ABBREV('PRINT','Pri')      ->    0
ABBREV('PRINT','PRI',4)    ->    0
ABBREV('PRINT','PRY')      ->    0
ABBREV('PRINT','')         ->    1
ABBREV('PRINT','',1)       ->    0

Note:  A null string always matches if a length of 0 (or the default) is used.
  This allows a default keyword to be selected automatically if desired;
  for example:

    say 'Enter option:';   pull option .
    select  /* keyword1 is to be the default */
      when abbrev('keyword1',option) then ...
      when abbrev('keyword2',option) then ...
      ...
      otherwise nop;
    end;

For more complete information, see the z/VM: REXX/VM Reference.