Would I be right in thinking that Scottish imposing MDI,s is the equivalent of EDI holding at Tweed and Stira
Well, both are a result of too many aircraft fitting into a given bit of airspace at any one time but there the similarities end. The holding happens when more aircraft arrive at the holding fixes than can be accepted by Edinburgh on a free flow basis. Aircraft enter the hold and await their turn.
MDIs, on te other hand, are a way of spreading out the outbound traffic that could otherwise overload the Galloway sector.