Man pages matching name fmemopen in section 3:

fmemopen.3.en	debian 10 / manpages-dev
fmemopen.3.ja	debian 10 / manpages-ja-dev
fmemopen.3.en	debian 11 / manpages-dev
fmemopen.3.ja	debian 11 / manpages-ja-dev
fmemopen.3.en	debian 12 / manpages-dev
fmemopen.3.fr	debian 12 / manpages-fr-dev
fmemopen.3.ja	debian 12 / manpages-ja-dev