An event flag is a synchronization object used for signaling between threads. Threads can wait on an event flag by calling wait. When some other thread signals the flag, the waiting threads proceed with their execution. The event flag is initially in the unsignaled (reset) state.
With the IBM® Rational® Rhapsody® implementation of event flags, at least one of the waiting threads is released when an event flag is reset. This is in contrast to the regular semantics in some operating systems, in which all waiting threads are released when an event flag is reset.
The operating system factory's createOMOSEventFlag method creates a new event flag.