SASKATOON9999
For example, you may find B752/3 is heavy in Austria. That was on request from LOWW APP, after an incident they had with it. So, now on our radar label (Beograd ACC) we have combination of both M and H for B752/3, depending where it's coming from (actually, that's how we find out about Austrians). As far as I was told, the heaviest version of B757 reaches 113.000 kg, so, according to that, it's medium, but due wake it creates, some ATCs are considering it as H.