I haven't seen this post on the forum here. But here you go.. http://www.dtsonline.com/company/pre...cID=1&yID=2004 http://www.dolby.com/about/news_even..._23.09.04.html Summary: Dolby Digital Plus(*) and MLP Lossless are mandatory for HD-DVD. Dolby Digital and DTS are mandatory for Blu-ray. Optionally DTS++(**) (DTS extensions) for both formats. *Dolby Digital Plus is backwards compatible with Dolby Digital and offers more channel and higher bit-rates. **DTS++ is the collection of all DTS extensions, such as higer data rates ( Rates greater than 1.5Mbps), higher sampling rates (like DTS 96/24), more channels (up to 7.1) , lossless capabitily and maybe others.