Everyone's been talking about "all 21 chapters" of the physics book I've been working on, even though, until today, all the chapter listings I had seen only went up to chapter 20. I figured that either the listings were wrong, or I was mishearing when they said 21, or someone had made a typo, or something.
Today I got the final table of contents for the book. Guess what? They only go up to 20. But there are 21 of them.
There's an extra chapter between 10 and 11.
The title of the chapter is 'Special Relativity'.
Guess what it's called?
'Chapter R: Special Relativity'.
Guess how I found out it was there?
The build script chokes on 'R'.