There has been a push in the no-Intro world to pull apart a number of DATs into two separate DATs.
A number of DAT will be splitting into:
Machine Life DAT and an After Market DAT
Where Machine Life is real 'games' released for the system during its actual release life cycle.
After Market is anything else like games made by individuals more recently.
For example: A2600 will split into:
A2600 <-- Known as the Machine Life DAT and
A2600 (Aftermarket)
DatVault will be making this change in the next couple of days.
The DATs you have today will be updated to the Machine Life DATs.
And you will soon see new DATs appearing as the Aftermarket DATs.
Many people are saying they are really only interested in the original content for these older systems, which is why the aftermarket DAT has been split out.