Man pages matching name isfdtype in section 3:

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