VMS Help :=  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    Defines a symbolic name for a character string value.

    Format

      symbol-name :=[=] string

      symbol-name[offset,size] :=[=] replacement-string

                                   NOTE

       Compaq advises against assigning a symbolic name that is
       already a DCL command name. Compaq especially discourages
       the assignment of symbols such as IF, THEN, ELSE, and GOTO,
       which can affect the interpretation of command procedures.

  Additional Information (explode) :

• Parameters
• Examples