mame2000, mame2003 and mame2003-plus carry a DAT their code moved past. Their parents and BIOS sets now come from src/driver.c and src/drivers/ at the pin, named by the src tree sha. The DAT is still read to report gaps. FBNeo DATs are read one namespace each, console sets keyed by driver. A BIOS with no dumped ROM is no longer listed.
The games index now names, per arcade core, the game sets that load no
BIOS set and every BIOS set, so a set on a card the DAT does not know is
told apart from one that needs nothing. Each board default core of a rom
folder gets its own fallback set, and index.json maps every folder name
a setup uses to its systems, for a games folder on a computer.
Abdessamad Derraz