I always read ds to mean darling son and dd to mean darling daughter. I could be wrong though, that was more of an assumption on my part.
Other HOD lingo I had to learn this year (our first HOD year)
LHTH=Little Hands to Heaven
LHFHG=Little Hearts for His Glory
BLHFHG=Beyond Little Hearts for His Glory
BHFHG=Bigger Hearts for His Glory
CtoC=Creation to Christ
RtoR=Resurrection to Reformation
RevtoRev=Revolution to Revival
DITHOR=Drawn into the Heart of Reading
dh=darling husband
TRL=The Reading Lesson
RME=Reading Made Easy
IEW=institute for excellence in writing
I'm sure this is not a complete list. If you have any specific ones you need clarified, just ask. The ladies on this board are wonderfully helpful.