... user-defined data file formats . ... better integration with a user's analysis routines To add such functionality to SAOimage, we developed the XPA Messaging System that allows X programs to define points of public access through which data and commands can be exchanged with external programs. ... We have utilized XPA to develop "SAOimage: The Next Generation" (SAOtng), an extensible image display service that can cooperate with other processes and programs. ... SAOtng help pages . ...