Intellectually, I really can understand the concise usefulness of ICONCLASS, especially for computerized iconographic indicies. It's a number/letter system for categorizing iconography, so as to standardize the terminology used to refer to it, and has been around a while now (in early forms, since the 1950s). Still, there's something fundamentally odd about describing a picture with it. For example, a 26B2 is a rainbow, while a 45K231 is a siege engine, and a 46A7 is a crowd or a mob. It's true,, it's much more coompact to say that a 26B2 over a 45K14 filled with a 46A7, and with a 45D21 and a 45K231 in the foreground is somewhat more compact than describing an image as containing a rainbow over a mob-filled fortified city with land-forces and a siege engine in the foreground is. But at the same time, it loses a certain immediate comprehensibility.