Here's an old (unofficial) Q&A that mentions Pockets being Front Line Locations.
O11.605 & O11.6066 O11.605 says that with a properly determined perimeter "loop" you "will
be able to start at any Front line Location, and by moving only into an adjacent Front Line
Location, and never re-entering the same Front Line Location, eventually end up back at the
starting Front Line Location." Consider the Russian Pocket #1 in the EX: If you start at any
Location in this pocket and move to adjacent Front Line Locations, you will have to re-enter
hex H43 before you have ended up back at the starting Location. Is this example wrong?
A. No; single-hex-width pockets will always have this affect. [Compil3]