Invisible by default; this is a pop-up display of Planetary Classifications from Star Trek. Each display appears by a trigger word and is cleared by typing ".". The triggers are:

ClassA
ClassB
ClassC
ClassD
ClassE
ClassF
ClassG
ClassH
ClassI
ClassJ
ClassK
ClassL
ClassM
ClassN
ClassO
ClassP
ClassS
ClassT
ClassX
ClassY

To clear the displays type period ".".