Arguments

context-symbol

   Specifies a symbol that DCL uses to store a pointer into the
   system's list of clustered nodes. The F$CSID function uses this
   pointer to return a cluster identification number.

   Specify the context-symbol argument by using a symbol. The first
   time you use the F$CSID function, use a symbol that is either
   undefined or equated to the null string.

   If the context-symbol argument is undefined or equated to a null
   string, the F$CSID function returns the cluster identification
   number of the first system in the system's cluster node list.
   Subsequent calls to the F$CSID function will return the cluster
   identification number of the rest of the nodes in the cluster.