Template:M summ EUA Annex Suspension
A Suspension Event happens when the official infrastructure falls over so that the parties can’t transfer Allowances to settle a Transaction. It is the fault of neither party — therefore to be distinguished from a Failure to Deliver, which generally will be — and while there is overlap between Settlement Disruption Events and suspension Events (in that both are things beyond the parties control) Suspension Event, being narrower and related to the failure of official infrastructure, trumps Settlement Disruption Event where they both apply to the same event. Generalia specialibus non derogant, I suppose.
We have compared Settlement Disruption Events and Suspension Events here.