17.2.2 %IDENT Directive
  The %IDENT directive identifies the version of a program
  module. The identification text must be a quoted string of
  up to 31 characters. The information contained within the
  identification text appears in the listing file and the object
  module. Thus, the map file created by the OpenVMS Linker
  also contains this information.

  The identification text appears in the first 31 character posi-
  tions of the second line on each subsequent listing page. In the
  following example, the %IDENT information appears as the
  first entry on the second line of the listing. The information is
  also included in the object module if the compilation produces
  one. If the linker generates a map listing, this information
  also appears there.
  %IDENT "V5.3"
  SUB PAY
      .
      .
      .

  If your source module contains multiple %IDENT directives,
  BASIC signals a warning and uses the version specified in the
  first %IDENT directive.