Man pages matching name pmsortinstances in section 3:

pmSortInstances.3.en	debian 10 / libpcp3-dev
pmsortinstances.3.en	debian 10 / libpcp3-dev
pmSortInstances.3.en	debian 11 / libpcp3-dev
pmSortInstances.3.en	debian 12 / libpcp3-dev