Man pages matching name mq_open in section 2:

mq_open.2.en	debian 10 / manpages-dev
mq_open.2.ja	debian 10 / manpages-ja-dev
mq_open.2.en	debian 11 / manpages-dev
mq_open.2.fr	debian 11 / manpages-fr-dev
mq_open.2.ja	debian 11 / manpages-ja-dev
mq_open.2.en	debian 12 / manpages-dev
mq_open.2.fr	debian 12 / manpages-fr-dev
mq_open.2.ja	debian 12 / manpages-ja-dev
mq_open.2.ru	debian 12 / manpages-ru-dev