Meta key

For now, some notes about the development of a "meta key" concept. Roughly in chronological order.

• "Meta Hand" on the TX-2 keyboards.
• META on the LINC keyboard.
• ITS and its preceding PDP-6 software uses Teletype model 33 Altmode key as a command prefix.
• EDIT on the IMSSS custom Datamedia keyboard for use with TVEdit.
• META modifier on the SAIL keyboard.
• META modifier on the Knight keyboard; used with EMACS as an alternative to the Altmode prefix. Also TOP.
• META modifier on the Kulp "space-cadet" keyboard. Also TOP, GREEK, SUPER, HYPER.
• Stanford SUN workstation proposal from 1980 mentions a META key.
• Sun-2 keyboard has modifiers LEFT and RIGHT. Subsequent Sun keyboards have the diamond symbol.
• The X Window System protocol has five "mod" bucky bits, of which the first is usually mapped to Meta and/or Alt.