3. The XAS environment
The XAS system is unlike packages with an overarching monitor (like the
MIDAS monitor or the
and also unlike monolithic programs like
but is a collection of cooperating programs invoked from the
usual Unix shell or VMS DCL prompt.
These program may communicate between each other in several ways
A XAS environment variable is assigned a value with the
command and is deleted using the
of XAS and system environments is described elsewhere.
One can also consult a list of all known global variables in
alphabetic order or