Dutch Multi 2C

meaning:
two-way multi: weak two diamonds or strong 2C
answers:
weak hand vs. weak hand (0-15 hcp) 
2C 2D = negative 0-15 hcp
weak hand vs. strong hand (16+ hcp)   
2C 2NT = asking for feature
2C 2H/2S/3C/3D = 16+ hcp, 5-carder
strong hand vs. weak hand (0-15 hcp)
2C 2D - 2H/2S/2NT/3C/3D = strong 2C opener
strong hand vs. strong hand (16+ hcp)
if positive response (16+ hcp) versus strong 2C opener is given, some bid like 4NT or 7NT should be bid - but it never happends ;-)

Suggested defense

The more probable possibility weak 2D is assumed, so
Db = like 2D Db, 2H/2S = like 2D 2H/2S, 2NT = like 2D 2NT, etc.
2C 2D = strong Take-Out, Game-Forcing (!)
4th in seat : 2C Ps 2D <?> = like 2D opening
6th in seat : 2C Ps 2D Ps - Ps Db = For Penalty