What does DAL in AP_DAL mean?

Ground Control Software Andropilot
1

I have recently been studying the format of ardupilot log.
I would like to ask what the DAL in AP_DAL means?
The most likely meaning found so far is Data Access Layers.

2

probably Data Abstraction Layer

3

@LiaoYiDe Have you figure out what does DAL mean?

Direct Access/Abstraction Layer for interface encapsulation？