I'm making plans to build some 14x17 holders, and I'd like them to meet ANSI standards, but when I look at this page, it says the 'exposure height' is 17.062 inches. I have some 14x17 x-ray film, and it measures 16.906 inches long. How's that work?

Is x-ray film different from standard film (I didn't think it was); or is this page incorrect; or are the ends of the film not captured by the holder; or am I missing something it the definition of 'exposure height'?