Table 2

RCVEF:               set the receive local event flag when a message is
                     received.
mbxid:               the mailbox id.
func:                function to be performed; in this case, read a virtual
                     block.
msgque[qtail].iosb:  the address of the I/O status block of the next entry in
                     message queue. Final completion status of SYS$QIO will
                     be written here.
receive:             the address of the interrupt service routine.
mbxid:               argument to be passed to the interrupt service routine.
msgque[qtail].msg:   the address of the message block of the next entry in the
                     message queue. The message received will be written
                     here.
sizeof(MSGBUF):      the size of the buffer area into which the message is
                     written.