newbie

I just signed up to this community and read a very good article about user Sidarth (I believe) and his experience studying for and taking the GMAT. In his article he uses a lot of abreviations like the following phrase, "CR and SC are mostly [tooltip=Official Guide]OG[/tooltip] standard, and GMAT paper test standard" I could not figure out what these were. What is [tooltip=Official Guide]OG[/tooltip], CR and SC? I'm sure there are more abreviations so I'd like to compile a list to document all of these. Thanx