This has probably been raised before in these forums, but surely, raw is not an abbreviation or acronym? I’ve always thought that while JPEG is an abbreviation of Joint Photographic Experts Group, raw simply means that the data from the camera has not yet been processed (or “cooked”) yet, and therefore, the word should not be capitalised? I think the boat has probably sailed on this question, but I shall continue to be pedantic and refer to raw files!
For what it's worth, our house style is "Raw."
There's no reason for it to be all caps, but to make clear that we're talking about the filetype and because the data contained isn't necessarily unprocessed, we treat it like a proper noun, rather than an adjective.
I'm not posting this to start a discussion of whether we
should take this approach (and I know of at least a couple of locations on the site where it's hard-coded as all caps). But that's our house style and has been for at least 15 years.
Richard - DPReview.com