An EventStubLib.Handle represents a handle used to either marshal and unmarshal events into and out of EventRd.T structures. Here we reveal that a handle h consists of an event writer h.wr used for marshalling an event and an event structure c.event used for unmarshalling an event.\ttindex{EventStubLib.Handle}

INTERFACE EventHandle;

IMPORT Event, EventWr, EventStubLib, Thread;

REVEAL EventStubLib.Handle <: Public;

TYPE
  Public = Thread.Mutex OBJECT
    cur: CARDINAL;
    event: Event.T;
    wr: EventWr.T
  END;

END EventHandle.

The two parts of the Public object are disjoint. wr is used when an event is being created. cur and event are used when an event is being read. cur is the offset of the EventStubLib.Handle in event.rd. This must be maintained here because there can be multiple simultaneous readers of an Event.T.

There are two final clauses in the specification of the message writer wr and the message reader event.rd in an EventHandle.Public. First, their buffers must be word-aligned in memory. More precisely, if byte i in the data stream is stored in the buffer at memory address j, then i and j must be equal modulo the machine word size. This requirement allows optimized stubs to read and write scalar values from the buffer efficiently.\index{buffered streams}.