Argument

 

efn

   OpenVMS usage:ef_number
   type:         longword (unsigned)
   access:       read only
   mechanism:    by value
   Number of the event flag to be set. The efn argument is a
   longword containing this number; however, $SETEF uses only the
   low-order byte.

   Two local event flag clusters are local to the process: cluster 0
   and cluster 1. Cluster 0 contains event flag numbers 0 to 31, and
   cluster 1 contains event flag numbers 32 to 63.

   There are two common event flag clusters: cluster 2 and cluster
   3. Cluster 2 contains event flag numbers 64 to 95, and cluster 3
   contains event flag numbers 96 to 127.