Mr. R350

I need to know how the regeneration process of the particulate filter takes place in a new R350? I am specifically interested in where the fuel is injected that generates the heat that burns away the accumulated soot. As far as my understanding this can happen in one of two ways:

(1) Fuel is injected into the cylinder after compression and with the exhaust manifold open the extra hot vapors heat up the particulate filter burning away build up soot.

OR

(2) Same as above except fuel is injected directly into exhaust stream instead of in cylinder.

How is this done in the R350?

Thanks for you help.