This article is from the RCA SelectaVision VideoDisc FAQ, by firstname.lastname@example.org (Tom Howe) with numerous contributions by others.
Some of the later CED's state on the caddy: "This VideoDisc has a
matrixed surround soundtrack," but in fact, any stereo disc of a movie
released in Dolby should still have the surround sound information
encoded on the stereo channels. The CED Title Database indicates which
discs should be playable in Dolby Pro Logic surround sound, according to
Dolby Laboratories master list.