Library /sys$common/syshlp/lse$menu.hlb SET_LANGUAGE_OPTIONAL_DELIMIT  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  Syntax:  SET LANGUAGE OPTIONAL DELIMIT begin_string end_string
              defined_language

  Specifies starting and ending strings that delimit optional
  placeholders.

  Note that you cannot use any character that you used as a comment
  delimiter.