D3 (163) - Belts: How many?
 

I'm familiar with my engine having a timing belt, and the (outer) aux belt. It seems there's also a third one.

Attached is the list of belts and part numbers from my service in 2016.

What is this additional belt and what are the service intervals for it?

I have a D5 but on that the third belt is for aircon compressor, driven from the power steering pump. Service interval is maybe 60k kms, or so.