This short paper is not written as a tutorial. It is intended for Modula-2 experts who are already familiar with the coroutine concept and its Modula-2 implementation.

After introducing the implementation of the coroutine primitives TRANSFER and IOTRANSFER, the author describes a new abstract machine that implements the following extended primitives: InitialTransfer, Transfer, LastTransfer, AttachEvent, and DetachEvent. Even though the proposal substitutes five primitives where only two existed, it is simpler to work with. The programmer is relieved of the necessity of keeping track of the active coroutine.

The paper is tersely written and therefore hard to follow.