An EASA Permit is the document that is being used in EASA for aircraft not holding a CofA or delegated to national authorities (that is, Annex II aircraft).
It has replaced A and B conditions for what would otherwise be CofA aeroplanes. In other words - post maintenance and experimental flight testing and ferry flights. If it's also being used for aircraft that for some obscure reason aren't Annex II but don't hold a CofA that makes some kind of sense.
I believe that the EASA permit was launched on them at very short notice, has caused some considerable difficulty to our friends at CAA who are running around desperately trying to keep many aeroplanes in the air. Personally I think that in the long run they'd do everybody a favour by not trying to paper over the cracks of EASA and showing everybody what a mess this is more clearly than they have.
G