Mir-10T 27mm/3.5 is a modification of Mir-10A designed to TV camera (24x32).
T lens has higher resolution : Mir-10A has (center/edge) 40/20 whereas Mir-10T has 47/27. Also T has focal lenght 27,39 whereas Mir-10A has 28,02.
This serie of TV lenses come with big hood that fit 24x32 (so it make a little vertical (on left and right) vignetting on 24x36 camera).
Diaphragme is also different (all the lenses of this serie share the same diaphragme)