HELP POP_TIMEOUT                                Revised by Fran Evelyn, July 85

The variable POP_TIMEOUT, which holds a procedure, is part of the POP-11
facility for timing out a read from the terminal. The number of seconds in
which a read times out is specified by setting the value of the variable
POP_TIMEOUT_SECS; the default value of this variable is FALSE.

When a timeout occurs the procedure held in POP_TIMEOUT is called. The value
of POP_TIMEOUT is user-assignable; the default is the do-nothing procedure
*IDENTFN.

Exiting normally from this procedure inside *CHARIN or *RAWCHARIN will cause
the read to be re-tried if no characters have actually been read before the
timeout. Exiting inside *SYSREAD will cause the number of characters read
before the timeout to be returned.

(N.B. On VMS ONLY this facility is independent of *SYSSETTIMER, and will
therefore not interfere with other procedures using this. On UNIX it is not
independent.)

See also
HELP *INTERRUPT      - on POP-11 interrupt procedures
HELP *CHARIN_TIMEOUT - waits a specified time or until a character is input
HELP *SYSSLEEP       - suspends the current process for a specified period
HELP *SYSHIBERNATE   - suspends the current process until an interrupt occurs
HELP *SYSTIME        - returns total CPU time for current POPLOG system run
HELP *SYSSETTIMER    - calls a procedure when a specified time has elapsed
