The Douglas measurement for fallow deer is quite complicated and includes dimensions such as length of each antler, length of points, dimensions of the antler palm, number of palm points, etc. All of these measurements contribute to the DS which must be given by a qualified scorer to be official. However many hunters learn the basics of the DS system for the game they hunt so they can make relative comparisons with the rough score that they take. You can get a hold of the DS booklet (tells you how to score) from the Australian Deer Assoc.

Hope this helps