This command was removed from CIAO at version 3.0.2.
The PLOTX command has been disabled in order to
lessen confusion in visualization. Plots are done using the
ANALYSIS setting, if applicable, and in channels
otherwise; see "ahelp analysis" for more information.
NOTE: A bug in CIAO 3.1 does not allow for plotting the PHA data in
the channel space when the instrument model is specified.