14.5. Variations on basic message passing
A message passing service may be provided with variations on the scheme described above, in order to satisfy the requirements of the systems which will use it. The reasons for these variations include the following. Note that the process address spaces may be on the same or on different computers.
A process may need to be able to send a message to more than one process (Section 14.5.6).
Processes may not want to commit to an indefinite WAIT for a single, specific message (Sections ...