USER OPTION [N1 N2] -- Edits/lists user defined commands.
Parameters:
OPTION -- Option determines the action to take.
Current options are:
LIST -- List the user defined commands.
CLEAR -- Deletes all the user defined commands.
DELETE -- Deletes a range of commands.
N1, N2 -- If the 'DELETE' option is specified, then a range of
commands should be given.
This command belongs to the class: information