Man pages matching name marpa::r2::bnf in section 3pm:

Marpa::R2::BNF.3pm.en	debian 10 / libmarpa-r2-perl
Marpa::R2::BNF.3pm.en	debian 11 / libmarpa-r2-perl
Marpa::R2::BNF.3pm.en	debian 12 / libmarpa-r2-perl