All Dolby EX tracks are matrixed - the Dolby Digital format is limited to 5.1, so the surround back has to be matrixed into the surrounds. DTS ES is somewhat different (you can poke through this PDF file if you want - I only had a chance to skim it, so didn't get much out of it except to say that DTS ES has the capability of a truly discrete 6.1 signal).