Library /sys$common/syshlp/basichelp.hlb Qualifiers, VARIANT  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  Lets you specify  a  value  for  the  lexical  function  %VARIANT.   The
  %VARIANT   function   allows   you   to  conditionally  control  program
  compilation.  The %VARIANT  function  returns  the  value  specified  at
  compile-time  with  the  COMPILE/VARIANT  command  or  set  with the SET
  command.

  Format

      VARIANT { : } int-const
              { = }