Pan cels are just what they sound like; cels that 
the camera "panned" over (or had the intention of 
panning over).

They are almost always one long sheet; they are 
not "connected". HOWEVER, if a pan cel has more 
than one layer, they layers themselves may not 
always be the same size. This could account for 
the "attached" condition you have, as often these 
layers are stored and attached oddly due to their 
oddity.

Also, there is no uniform length for a pan cel; 
it doesn't have to be over 14 inches. It can be 
any size, really.

-Misha