Been looking for some basic explanation of the numerous sound formats currently around. At the risk of exposing myself for the novice that I am, could some of you please fill in the gaps below and correct anything else about which I have been mis-informed. Dolby Prologic; Available from any stereo source with the approprate decoder. (If this is so, why do some broadcasters advertise programmes "In Dolby Surround"). It produces front stereo, centre and mono sound of limited band width to a pair of rear speakers. Dolby Prologic II; As above but with a "processed" stereo signal to the rear speakers. Dolby Digital; Front and rear (full band width) stereo + centre. Dolby Digital EX; ? DTS; Same result as DD but slightly different decoding method. DTS-ES Discrete; ? DTS-ES Matrix; ? DTS-ES NEO; ? Can somebody also explain why some discs which I have seen, indicate on the box that the sountrack is in mono, whilst also having the Dolby Digital logo on them? Basic I know, but then that should make it all the easier for you !!