I'm trying to improve the scanf documentation in glibc regarding the "'" and possibly "I" flags: https://sourceware.org/ml/libc-help/2015-10/msg00003.html The scanf(3) page seems to be a partial copy of the glibc texinfo manual, so the improvements should apply to it. I'm using this bug as a remainder; for now, I think we should wait until the glibc manual is updated.
I'm closing this bug as it's been inactive for some time. But, I have added the following text to scanf(3): · For decimal conversions, an optional quote character ('). This specifies that the input number may include the thou‐ sands' separator as defined by the LC_NUMERIC category of the current locale. (See setlocale(3).) The quote charac‐ ter may precede or follow the '*' assignment-suppression character.