What do you mean when you say a layer is a 
photocopy? Photocopy on paper? Im just a bit 
confused since the transfer of lines to a cel is 
usually done with a photocopier. I have at least 
one cel of my own that has a layer with just some 
lines and no paint that I can think of offhand. I 
remember it because it was stuck to another layer 
and was a bit offset -_-!

I think it was possibly used to align the action 
of the 2 characters in the cel. It also defined a 
few lines that weren't on on of the props(a box, 
akari's house, heh). Not sure if any of this 
helps.