What is the "Delivery supplement"?

[OnAFlyer]

I'm not a fan of the whole delivery supplement shambles,more for the way it was sold and the personal loss of my shift allowance than anything else but in a few years time(if it's still around) once people forget that we used to get paid separately for D2D...members will wonder how the union managed to get us a supplement for basically doing our job.
Does a Tesco employee get a "shelf stacking" supplement?

Shame it wasn't put into basic wage though, because when we're privatised its things like the supplement that will start disappearing.