xsm is a session manager. A session is a group of applications, each
of which has a particular state. xsm allows you to create arbitrary
sessions - for example, you might have a "light" session, a "development"
session, or an "xterminal" session. Each session can have its own set of
applications. Within a session, you can perform a "checkpoint" to save
application state, or a "shutdown" to save state and exit the session. When
you log back in to the system, you can load a specific session, and you can
delete sessions you no longer want to keep.