======Synopsis:======
[[window]] clearlevel <level(s)>

======Description:======
The __WINDOW CLEARLEVEL__ operation removes all items from the
[[WINDOW LASTLOG]] whose output level is in the level mask.
You can specify multiple levels by comma-separating them,
Removing things from your lastlog also removes them from your
scrollback and your screen as well.  This is useful for making 
certin types of output go away

Example:
    /window clearlevel JOINS,PARTS,QUITS

======History:======
The /WINDOW CLEARLEVEL operation first appeared in EPIC5-2.1.6