I don't have my copy directly in front of me at the moment, but if I remember correctly it does make reference to Federal Issue Frock coats having 7/8th inch buttons as the standard size button on the front and in the rear. This has always perplexed me as well as I keep thinking I'm reading it wrong (which isn't impossible!) While the CRRC is an EXCELLENT resource that I myself look to first whenever I have a question about something, I don't think it should the end all be all of gear questions. There are simply too many variations of everything that was issued throughout the war to expect a few pages in the larger compendium to cover all. Each section is a superb snapshot of the construction, materials, and uses of the equipment of the federal infantryman, but anyone of those sections could easily be expanded into a book of its own i.e. Paul Johnson's book on cartridge boxes, Gaedes book on shelter halves, or the books out there on canteens.