But it's not a lot of space for documents of hundreds of pages, so typical customers who were using FrameMaker to write user manuals for their products had to use "book" files to tie together individually edited chapter files. Then, once in a while you'd have to push the "generate" button on the book to get all the page numbers consistent between chapters, all the cross-references updated, and generate the updated Table Of Contents, Index, etc. You're welcome.

But there's a potential degenerate case where Chapter 1 might have a forward reference to Chapter 2 ("see page 209"), but due to some editing in Chapter 2, the referenced material now on page 210. Well, in some fonts, "209" is wider than "210" (since "1" can be skinny). So, during the Generate operation, the reference becomes "see page 210". But there's some tiny chance that this skinnier text changes the including paragraph to have one less line, so there's some tinier chance that Chapter 1 takes one less page, so Chapter 2 starts one page earlier, and now the referenced material is back on page 209. So now we're in a loop.

This was such an unlikely edge case that nobody else noticed that it even existed, much less that it was detected. I didn't bother with a fancy error message; it would just give a little one-word popup: "Degenerate". Years later, mild panic ensues when a customer calls in, irate that the software is calling them a degenerate. (And it wasn't even a real example, just some other bug that triggered it.)

On the other hand, it seems that you are, in fact, correct. Oh, well.