CUT10 is a cutscene from Tomb Raider III that was scrapped during development.
The cutscene was first described in Vicky Arnold's original script for the game, simply stating that "Lara is waking up inside a small prison-like room" during the night.
The cutscene was built and can still be found in the game as late as the October 5th beta build. It is however incompatible with this build if one tries to access it. Fan Gh0stblade is said to have loaded the cutscene into an earlier Electronic Computer Trading Show build of Tomb Raider III. It matches what was described in the original script.