The terminology problem is that the acronym MAS is already used for a different device. The original MAS is a voltage supply relay that combined the OVP, the FP, and Klima relays with a couple new functions in about 1990 300Es.
There is only one air mass meter/mass air flow sensor/air flow meter. The first term describes the device so I prefer it. To change it to Mass Air Sensor doesn't bother me, but if I didn't know what it was the name wouldn't tell me. After all, what is mass air. Air mass is defined by the words. The actual name was complicated by the fact that early devices were just air volume meters. They moved a door for sensing. The newer devices do better than just volume by finding mass. Volume times weight equals mass (or some such). Early sustems figured all air had the same weight. That worked for pre lambda cars.
Bosch Master, ASE Master, L1
33 years MB technician