Glibc change exposing bugs

Before you say that a man page is not authoritative, I don't know the answer to that but it depends on your Linux vendor. In practice you will want to follow the major standards and consider otherwise to probably be an error in the man page; however, if you vendor says that X and Y are the documents, then that is what you go by (perhaps bringing up doubtful points to your vendor's attention). In particular, if you don't like a vendor that hacks Linux to bypass certain standards, then change vendors or ask for help in identifying these hacks.