Command_File_Specification

   If indirect command procedures are used, you may need to put
   quotes around file specifications.

   The following examples show the differences in output between
   TRADITIONAL and EXTENDED parse styles when using the same command
   file, SS.COM:

          $ create ss.com
          $ if p1 .nes. "" then write sys$output "p1 = ",p1
          $ if p2 .nes. "" then write sys$output "p2 = ",p2
          $ if p3 .nes. "" then write sys$output "p3 = ",p3

   o  Setting the parse style to an ODS-2 environment and running
      SS.COM, the following output occurs:

             $ set process/parse_style=traditional
             $ @ss ^ p2 p3
             p1 = ^
             p2 = P2
             p3 = P3

      Note that the circumflex (^) is the first argument, and that
      the case is not preserved for the p2 and p3 variables.

   o  Setting the parse style to an ODS-5 environment, the following
      output occurs when running the same command procedure:

             $ set process/parse_style=extended
             $ @ss ^ p2 p3
             p1 = ^ P2
             p2 = P3

      Note that the command procedure recognizes the circumflex (^)
      as the escape character, and "^ P2" is the first argument.

   o  Adding quotes to the circumflex (^) produces the following
      outcome:

             $ @ss "^" p2 p3
             p1 = ^
             p2 = P2
             p3 = P3

      Because the circumflex (^) is within a quoted string, it is
      not treated as an escape character.

   o  Adding quotes to the p3 variable produces the following
      outcome:

             $ @ss "^" p2 "p3"
             p1 = ^
             p2 = P2
             p3 = p3

      Note that the case is preserved for the p3 variable.

   o  In an ODS-2 environment, the following command treats the
      circumflex (^) and the p2 and p3 strings as arguments, and the
      command procedure produces the following results:

             $ set process/parse_style=traditional
             $ @ss^ p2 p3
             p1 = ^
             p2 = P2
             p3 = P3

   o  In an ODS-5 environment, the circumflex (^) is treated as
      the escape character and DCL looks for the file "SS^_P2.COM",
      which results in the following error:

        $ set process/parse_style=extended
        $ @ss^ p2 p3
       %DCL-E-OPENIN, error opening USER$DISK:[TEST]SS^_P2.COM; as input
       -RMS-E-ACC, ACP file access failed
       -SYSTEM-W-BADFILENAME, bad file name syntax
 

Additional information available:

Case_Preservation_and_$FILE     Ampersand_Versus_Apostrophe_Substitution