What's between the outside and the inside of a toile bag?

suzy wong

O.G.
Apr 24, 2009
130
58
A quick question to anyone who has one or has seen one up close - what's between the outside and the inside of a toile bag to keep it rigid, and what's the lining made from? Is the bag scotch guarded or similar to make it stain resistant?

Sorry if this is covered elsewhere, but searching from hand-held is a pain.

Thanks in advance!