ARC (American Rottweiler Club) is currently in the middle of a bruhaha over tails and standards. According to some, the majority want to have any dog that's docked not be able to be shown in AKC/ARC shows. But yet, these same people want to breed to those tailed dogs. Hypocritical much?
The CKC (Canadian Kennel Club) has revised the standard to include tails and the FCI has as well. Here's the CKC version:
Tail:
The tail is normally carried in a horizontal position giving the appearance of an elongated topline. It is carried above the horizontal when the dog is excited. The tail is normally docked short close to the body, if left in natural condition, tail is level in extension of the topline; at ease may be hanging. A kinked tail or ring tail is undesirable. The set of the tail is more important than length.
Here's the FCI version:
TAIL : In natural condition, level in extension of the upper line; at ease may be hanging.