Template:M summ EUA Annex Scheme
The European Union Emissions Trading Scheme. For this you will want our Emissions Annex Anatomy - ISDA-focussed though it is.
Here is the EU ETS legislation including the vaunted Chapter II, which deals with aviation. that may help you if you are wondering, as we did for a cold hour on Monday morning recently, what an AEU Allowance is.