CdDN = Col de Dame Noir (Cuello de Dama Negro) is the black variety. Col de Dame Gris (CdDG) is the “gray” variety. Col de Dame Blanche (CdDB) is the “white” or green variety. They need a long season to ripen (CdDG- the least) but produce exceptionally wonderful figs even at a young age.
Herman says of them: “All three cultivars are the same, tight eye, no souring or splitting, solid interior, very good for the south”
The three Col de Damas are know for their outstanding taste, which is described as a Bordeaux Berry flavor  -“Sweet, with a berry taste which is rich...” They are not the sweetest figs around, but are sweet enough and have a slight acid kick that accents the berry taste in a unique way similar to an awesome strawberry jam. 
Several people have posted that their CdD (G/B/N) is the most delicious fig they grow.

I'm not in the club either and am just beginning to figure out what all the initials stand for. But I've been taking extensive notes from the posts I read and am happy to share them.