Luftwaffe map Locations
 

hello! having at last got familiar with the usual number/letter grid references, I have found the following reference for a claim on 17th February 1940 by Wolfgang Falck. I understood the letter I was not used for references, certainly later in the war. I believe it relates to the Fresian Islands but any advice about this lettering system or more precise location would be appreciated - especially if I am to encounter similar in future:

"Nordsee Pl. QU. Ida-Dora"

Thanks for your advice!

Regards "Squawk"