In Tom Clancy's (not very good) novel The Bear and the Dragon, he refers to one of the characters as a retired "half colonel." In the American military, a colonel is distinguished from the next-lower rank by being called a "full colonel" or a "full bird colonel" -- with reference to the eagle insignia which indicate colonelness. A lieutenant colonel, on the other hand, is referred to as a half-bird colonel, a light colonel, or a light-bird colonel, but not as a half colonel ... at least not in my experience.

Does yours differ? Is this another of those cross-Pond differences in slang?