... The XPA messaging system provides seamless communication between many kinds of Unix programs, including X programs and Tcl/Tk programs. It also provides an easy way for users to communicate with XPA-enabled programs by executing XPA client commands in the shell or by utilizing such commands in scripts. ... A program becomes an XPA-enabled server by defining named points of public access through which data and commands can be exchanged with other client programs (and users). ... XPA User Programs . ...