Hello all,

I recently purchased a cel that came with a 
sketch that had a whole bunch of   (plus) signs.  
The sketch on the corner has A2, A21 or A2- (I 
can't make it out) and under this number is A71-  
The actual cel number is A2 but the picture is 
not reflected on the sketch; just   signs are on 
the sketch which is around the picture of the cel 
if I put the cel on top of the sketch.  Could 
this mean that this is not the sketch of the cel 
or does it mean the cel is in various frames of 
the scene? Also, what does the   sign mean on a 
sketch in general?   

Thanks in advance to all that can shed some light 
in helping me into this matter.  I am very 
curious to know.