Map References in Luftwaffe Claim Tables

[squawk]

Good afternoon

Could I ask for your well informed help concerning the Luftwaffe map grid references which appear in their claim records? I have tried to understand it all but perhaps I am just getting too slow now!

On 24th February 1944 the night fighter ace VON-BONIN made two claims for 4 engined bombers brought down on the inbound route to Schweinfurt.

He states the locations were TN and TM which I thought related to the Jaegergradnetzkarte, and these were in the general direction of north and north west of Metz.

Now I am not so sure because I am told several maps were in use, and there do not appear to be any crashes attributed to night fighters recorded for these areas at that time.

Please, where approximately are TN and TM in relation to a modern civilian map?

Many thanks and regards

"Squawk"