The System area is used to enter and display in the name of the system.
You can browse a system by entering its name into the
System:
area. Whilst doing this you can press
Up
,
Down
or click 
to complete a partially specified name. This allows you to select from a list of all system names which begin with the partial input you have entered. See Completion for detailed instructions.
The members of the system are displayed in the tree area.
LispWorks IDE User Guide (Macintosh version) - 25 Nov 2011