1. An extended semaphore mechanism associated with an event whose occurrence is the detection in any of a first plurality of processes of a condition which is significant to any of a second of a plurality of processes, said extended semaphore mechanism comprising: a. first means for establishing on behalf of said any of said second processes an interest in at least one event occurrence in any of said first plurality of processes; b. second means, responsive to said any of said plurality of first processes and coupled to said first means, for monitoring on behalf of said any of said second plurality of processes for said event occurrence, in said any of said first plurality of processes; c. third means coupled to said first and second means for notifying said any of said second plurality of processes of said event occurrence in said any of said first plurality of processes; and, d. fourth means responsive to said third means for trapping said any of said plurality of second processes upon the notification of the detection of said event occurrence in said any of said first plurality of processes.