Receipt A process may wish to receive information from a subset of the set of ports available for receipt.
Systems differ in the amount of selectivity provided to a receiving process.
Some allow a process to receive either from a particular port or all ports. Others allow a process to specify any subset of the set of all ports. Still others allow a process to peek at the value of incoming messages and make its decision to accept or reject messages based on the contents of messages. If none of the ports has a message, then the process blocks. If several ports have messages, then one port is chosen non-deterministically.