I think correction layers are pretty cool, too! 
This is the only example of a correction layer 
that I have in my collection. The top picture is 
how the cel should look, and how it was filmed in 
the show. The bottom cel is what they covered up: 
her uniform is a totally different color, and the 
decorations on her sleeves are filled in. Sorry 
for the bad picture!

-lighthawk