There is three places for printing drivers:
DCP, FAX, HL, MFC printer driver download page(web archive);PT, QL, PJ, TD printer driver download page(web archive);PC-FAX driver download page(web archive).
Some drivers are PPD files or cupswrapper written in C-Shell language, they can be considered as source (see the “where are sources?” page).
Some drivers are duplicated for SI unit (mm) or Imperial units (inch), see the TD-2020 (web archive) for example.
Some Fax drivers are modem driver (FAX-modem), some other fax drivers are cupswrapper and LPR drivers (PC-FAX). Those ones are handled as printers.
On the new Brother™ web site, we can find PPDs that are not referenced on the old pages, like the BRP7000E_GPL.PPD [gz] on this page.
This is not studied now.
This is not studied now.