It's coded into the ECU's engine mapping, there's a switch on the clutch pedal which activates it (the same switch is also used to deactivate cruise control). The idea is to reduce the loadings on the dual-mass flywheel by raising the rpm a little from tickover.

When the clutch pedal is fully released, the rpm should drop back down again. It's actually a really useful feature in winter when there's snow or slush on the roads, you can get the car rolling easily without any wheelspin.

Many modern diesels do this - my previous Mindeo did, too.

As far as I'm aware, there is no real 'name' for the system, it's simply coded into the software that controls throttle settings, etc.

BMW have the same on manual gearbox diesels too - and I assume for exactly the same reason. If you're stopped, with the clutch FULLY depressed, and a gear selected, then the revs are about 800. Lift the clutch a bit, and they rise to 1100 or so.

It means that you can move forward in stop-start traffic, not touching the accelerator, but it puts a lot less stress on the DMF and (presumably) the clutch too.