Modifier Keys ... a brief history

One thing I recently learnt from using Macs. 

Modifier keys in general : 

Shift : 

- ISO Unicode symbol : ⇧ "Level 2 Select"

- notational equivalents : "shift X"

- origin : typerwriters

Control :

- ISO Unicode symbol : ⎈ "helm"

- notational equivalents : "control X", ^X, C-X, Ctrl-X

- origin : teletypewriters' appropriation of typewriters' "carriage control"

Alternative :

- ISO Unicode symbol : ⎇ "alternative key symbol"

- notational equivalents : "alt X", Alt-X

- origin : IBM "AltGr" for Alternate Graphic

Option :

- non-ISO Unicode symbol : ⌥ "option key"

- notational equivalents : "option X"

- origin : Apple [ a filled Apple logo ] for Closed Apple Key

- contemporary : Apple keyboards have combined this with Alternative

Command : 

- non-ISO Unicode symbol : ⌘ "place of interest sign"

- notational equivalents : "command X"

- origin : Apple [ an unfilled Apple logo ] for Apply Key

Also see : Fn