HD - High Definition
C - This program is copy protected and may not play back correctly if you try to record it
DS - You can hear this program in surround sound if your tv/home cinema system is compatible
DD - You can hear this program in Dolby Digital 5.1 if your tv/sound system is compatible
AD - You can choose to play an audio description over this program; a narrative soundtrack for the partially sighted
S - You can turn on subtitles for this program
W - This program is shown in widescreen
S - Sex or nudity
L - Strong language
V - Violent scenes
M - Material which is intended for a mature audience
(I suspect the last one may be knitting programes and the like 
)
Lifted from the book that came with my nice new shiny (and so far quiet) HD box that got installed yesterday.
