Clears (sets to 0) an event flag in a local or common event flag
    cluster.

    Format

      SYS$CLREF  efn

    C Prototype

      int sys$clref  (unsigned int efn);

1  –  Argument

 efn

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