Cels Forum

I could be wrong, but here's my take on it:

Cel Sequence:  Ever notice that sometimes there are cels out there
that look almost exactly the same?  They probably came from the same
sequence.  In animation, to make fluid motion, there have to be a lot
of cels, which are very much the same with slight differences.  A 
bunch of cels in a row are all from the same sequence.  They're usually
numbered in order, i.e. A1, A2, A3, A4, A5 etc...sequences can vary
greatly in length from that A1 End cel to the B47 + for some other
sequences.

End Cel:  Simply put, the cel at the End of a sequence.  This is 
usually marked simply with the word "End" or sometimes an "E" and of
course, the usual number (like C33 or A15 or something).  I think 
the 'end' is written there because there's no quick way of telling
based on the number.

Key Cel:  This is the one I'm the most unsure of.  A Key cel is usually
the start and end cel.  The end cel being as described above, I think the
start cel of a sequence is usually some letter followed by 1 (A1, B1 etc..)
Every now and then I see a cel actually marked 'Start.'  I think what 
makes these cels more desirable is that the key animators do the cel or 
drawing for the cel (something like that...I couldn't image them actually
applying the paint or something).  See, there are key artists/animators, but
the bulk of cels are done by assistants or 'in-betweeners' who fill in the
sequence (a more menial task I guess) between the key cels.

Keys