Proprietary Digital Satellite System Standard defined, owned and used by DirectTV. No public documentation available, here some guessed facts:
As Modulation Scheme DSS uses QPSK. Viterbi and Reed-Solomon Error Correction algorithms are the same like defined for DVB. Usually 1/2, 2/3 or 6/7 FEC, a different puncture rate and randomizer are used.
It utilises MPEG-2 like TS Packets that are 127 bytes long (instead of 188 Bytes as used in the case of MPEG-2/DVB -- as far we know 188 bytes packet length have been choosen there for compatibility with ATM networks).
For Program Service Information a so called "Master Program Guide" (MPG) is used, here all the information is stored on a single PID that is spread over NITs, SDTs, EITs in DVB MPEG-2 Transport Streams.