Man pages matching name cmtab in section 5:

cmtab.5.en	debian 10 / cryptmount
cmtab.5.fr	debian 10 / cryptmount
cmtab.5.en	debian 11 / cryptmount
cmtab.5.fr	debian 11 / cryptmount
cmtab.5.en	debian 12 / cryptmount
cmtab.5.fr	debian 12 / cryptmount