Man pages matching name fcvt in section 3:

fcvt.3.en	debian 10 / manpages-dev
fcvt.3.es	debian 10 / manpages-es
fcvt.3.ja	debian 10 / manpages-ja-dev
fcvt.3.pl	debian 10 / manpages-pl-dev
fcvt.3.en	debian 11 / manpages-dev
fcvt.3.es	debian 11 / manpages-es-dev
fcvt.3.fr	debian 11 / manpages-fr-dev
fcvt.3.ja	debian 11 / manpages-ja-dev
fcvt.3.pl	debian 11 / manpages-pl-dev
fcvt.3.en	debian 12 / manpages-dev
fcvt.3.es	debian 12 / manpages-es-dev
fcvt.3.fr	debian 12 / manpages-fr-dev
fcvt.3.ja	debian 12 / manpages-ja-dev
fcvt.3.pl	debian 12 / manpages-pl-dev
fcvt.3.pt_BR	debian 12 / manpages-pt-br-dev
fcvt.3.ru	debian 12 / manpages-ru-dev