Well, I actually have a background that was used
for multiple cel sequences.  It's marked on the
background (fairly simple background too!)  I
think what "laser copy" is supposed to mean is
that someone with the original background had a
version printed on suitable paper with a nice
laser copying machine (hence the name), usually
for the purpose of placing with other cels of the
same sequence (or sometimes different sequences or
shows!) for display or sale.  However, I think
what oion's refering to is also often called a
laser copy, but I suppose "laser background" would
be a more appropriate term.  Some productions have
been creating backgrounds on computer or with
computer help and then printing them out to go
with traditional cel art.  I don't know of any of
these shows myself, though I think someone once
mentioned WeiB Kreuz was one (anyone know?).

Keys