DAT file format documentation?

I’ve been searching on the web for almost an hour now, and I can’t find any documentation about the DAT file format (the ROM description files). Is there any dedicated place somewhere where such information can be found?

OK, it seems my question was misguided. Turns out there is no such thing as a file format for ROM DAT files. Everyone has their own (MAME, No-Intro, etc), it just happens they all call them “DAT files”.

/close