/sys$common/syshlp/helplib.hlb Lexicals, F$CSID, Example  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  $ IF F$GETSYI("CLUSTER_MEMBER") .EQS. "FALSE" THEN GOTO NOT_CLUSTER
  $ CONTEXT = ""
  $START:
  $   id = F$CSID (CONTEXT)
  $   IF id .EQS. "" THEN EXIT
  $   nodename = F$GETSYI ("NODENAME",,id)
  $   WRITE SYS$OUTPUT nodename
  $   GOTO start
  $NOT_CLUSTER:
  $ WRITE SYS$OUTPUT "Not a member of a cluster."
  $ EXIT

      This command procedure uses the F$CSID function to display
      a list of cluster system names. The assignment statement
      declares the symbol CONTEXT, which is used as the context-
      symbol argument for the F$CSID function. Because CONTEXT is
      equated to a null string, the F$CSID function will return the
      first cluster identification number in the cluster node list.

      If the F$CSID function returns a null value, then the command
      procedure either is at the end of the list, or is attempting
      this operation on a nonclustered node. The call to F$GETSYI
      checks whether the current node is a member of a cluster. The
      command procedure will exit on this condition.

      If the F$CSID function does not return a null value, then the
      command procedure uses the identification number as the third
      argument to the F$GETSYI function to obtain the name of the
      system. The name is then displayed using the WRITE command.