Man pages matching name barcode::datamatrix::constants in section 3pm:

Barcode::DataMatrix::Constants.3pm.en	debian 10 / libbarcode-datamatrix-perl
Barcode::DataMatrix::Constants.3pm.en	debian 11 / libbarcode-datamatrix-perl
Barcode::DataMatrix::Constants.3pm.en	debian 12 / libbarcode-datamatrix-perl