On this hidden page, not mentioned on any other Wiki 'main' page, you can find some MSX-BASIC extensions that don't have been released as BASIC extensions, but were part of a game or application. It should be exaggerate to include them on the page with the official MSX-BASIC extensions.

Generally, they didn't have been reused for other productions. There is however an exception for the popularity on the MSX scene, it's the CompileBGM BASIC.