Several routines are available for intra-node communication between
	console programs.  The messages are passed via mailboxes.
	cmu_connect connects a process to a specified mailbox.  Messages
	can then be sent and received with cmu_send and cmu_receive.  
	cmu_disconnect then allows detaching from a mailbox.  Callbacks
	can be specified for message notification.   Because of this, it is
	up to the user to use one mailbox to receive messages and another
	box to send messages.  Presently, the maximum message length is
	2048 bytes.
	See console page D111 (MAILTEST) for use of these CMU routines.

	send_rsx, receiv_rsx and lrdast allow a task to send, receive
	or check for messages from other applications.

	See also intro_acnet.

	These functions require the following include files:


	Related functions:

	cmu_connect, cmu_disconnect, cmu_empty_box, cmu_receive, cmu_send,
	lrdast, receive_rsx, send_rsx