A page like cerf(3), which says "not yet in glibc, as at version 2.12", provokes a name clash if some other library provides the missing implementation. The rpm package managers reacts to such name clash by suggesting to uninstall libc, which is no clever resolution. I suggest to resolve this problem by moving man pages of unimplemented functions to manual section 7, so that they can peacefully coexist in the shadow of section 3 pages provided by more specific libraries.
Hello Joachim, From my perspective, pages such as this are of marginal value, and if they provoke conflicts, I'd consider removing them. But... which other package provides this man page? Cheers, Michael
(In reply to Michael Kerrisk from comment #1) cerf(3) and related functions are provided by libcerf. Source available from http://apps.jcns.fz-juelich.de/doku/sc/libcerf. For binary packages, see links at bottom of that page. Removing the man pages of the non-implemented functions sounds like the easiest and most straightforward solution to me. Thanks for considering this further. Best regards - Joachim
Summary: These functions don't exist in glibc, aren't specified in C99 or C11 (those standards merely reserve the names for future use), cause package conflicts for libcerf (http://apps.jcns.fz-juelich.de/doku/sc/libcerf), which does provide implementations and man-pages for these functions, and cause confusion for readers who (not looking too closely at the page) wonder where the glibc implementation is. I've removed the cerf(3) and its links from man-pages. Sorry for the slow follow up.