tenia la misma duda y encontre esto
30.70 = original 4.2.2
30.71 = 4.2.2 OTA with camera update
30.B2 = 4.4 or 2nd OTA
30.B4 = 4.4.2 or 3rd OTA
30.B7 = 4.4.4 or 4th OTA
30.BC = 5.02 (leaked Brazil 5.0.2 update)
30.BD = 5.1 (leaked Brazil 5.1 update)
30.BE = 5.1 (2nd leaked Brazil 5.1 update - system 222.21.15.ghost_row.Brasil.en.BR )