Subscript letters were proposed as well: http://www.unicode.org/L2/L2011/11208-n4068.pdf but apparently "Not accepted: Because this has been controversial and is not directly related to repertoire under ballot, it is not appropriate to add it to Amd1 but may be considered for a future amendment" http://www.unicode.org/L2/L2012/12130-n4239.pdf
Looks like here's a recent draft for a new proposal: https://github.com/stevengj/subsuper-proposal
[0] https://en.wikipedia.org/wiki/ConScript_Unicode_Registry [1] https://en.wikipedia.org/wiki/Universal_Character_Set_charac...
Subscript letters were proposed as well: http://www.unicode.org/L2/L2011/11208-n4068.pdf but apparently "Not accepted: Because this has been controversial and is not directly related to repertoire under ballot, it is not appropriate to add it to Amd1 but may be considered for a future amendment" http://www.unicode.org/L2/L2012/12130-n4239.pdf
Looks like here's a recent draft for a new proposal: https://github.com/stevengj/subsuper-proposal