I'm used to military product designations, stores codes, and so on. They're usually all but incomprehensible except to those who've 'learned the code', and beloved of bureaucrats, pen-pushers and bean-counters. Just try ordering something essential, but not providing the precise twenty-nine-digit alphanumeric product code, and see how far you get!
Anyway, courtesy of an e-mail from a reader in the sandbox, I was intrigued to find a document that shows the vehicles used by the US Army and US Marine Corps, in all their variants. It's a long and complex document, but very interesting, in that it shows how a single basic design can be evolved and adapted to meet a multitude of needs. For example, take the High Mobility Multipurpose Wheeled Vehicle (HMMWV), better known simply as the 'Humvee'.
The page below shows how many variants of this design have been produced (open it in a new tab or window for a full-size view).
The source document also describes various families of trucks, wheeled and tracked armored vehicles, right up to main battle tanks, along with the full military designation of each variant. It may be boring to those who've never had to deal with such things, but to those of us who've worn uniform, it offers interesting reading.