Practically the restriction on training flights is what it means with respect to runways (I think it's 'unlicenced for commercial operations') however if it is in reference to an airfield as a whole there are other implications e.g. there is not necessarily fire and crash cover. I'm sure there are other things too but without consulting the ANO or the CAA I can't say offhand. Practically, for a regular PPL, it doesn't mean a fat lot.
[ 27 November 2001: Message edited by: DB6 ]