Man pages matching name pdf::fdf::simple::grammar in section 3pm:

PDF::FDF::Simple::Grammar.3pm.en	debian 10 / libpdf-fdf-simple-perl
PDF::FDF::Simple::Grammar.3pm.en	debian 11 / libpdf-fdf-simple-perl
PDF::FDF::Simple::Grammar.3pm.en	debian 12 / libpdf-fdf-simple-perl