The Top Key

By Xah Lee. Date: . Last updated: .

The Top key first appeared on SAIL Keyboard around 1970.

It is like the Shift key, used to input Math Symbols ∞ .

Then it appeared on Lisp keyboards

Seems, after the Space Cadet, the Top key disappeared. But the concept is picked up, as Apple's ⌥ option key 〔see Mac Keyboard Viewer〕 and AltGraph key. 〔see Alt Graph Key, Compose Key, Dead Key〕