The Get Event Flag routine allocates one local event flag from
    a processwide pool and returns the number of the allocated flag
    to the caller. If no flags are available, LIB$GET_EF returns an
    error as its function value.

    Format

      LIB$GET_EF  event-flag-number

1  –  Returns

    OpenVMS usage:cond_value
    type:         longword (unsigned)
    access:       write only
    mechanism:    by value

2  –  Argument

 event-flag-number

    OpenVMS usage:ef_number
    type:         longword (unsigned)
    access:       write only
    mechanism:    by reference

    Number of the local event flag that LIB$GET_EF allocated, or -
    1 if no local event flag was available. The event-flag-number
    argument is the address of a signed longword integer into which
    LIB$GET_EF writes the number of the local event flag that it
    allocates.