Codex Sinaiticus Correctors

I have in August 2015 adopted the sigla conventions of the NA28 for the correctors of Codex Sinaiticus in Revelation, and updated my apparatus accordingly:

ℵ*           4th century
ℵ¹           4th – 6th century (only one occurrence- in 21:4
ℵ²            7th century
ℵ²a          7th century
ℵ²b          7th century
אc            12th century