08:44 Jul 14, 2009 

I don't think this is necessarily a high-level cistern, just a separate water supply to the flush that is not necessarily included in the w.c. supplied. There is an applicable code "NF EN 38 : septembre 1992 - Cuvette de WC suspendue à chasse directe et alimentation indépendante". I haven't looked it up, but it might include direct mains feed without a cistern.

08:00 Jul 14, 2009 

Is this perhaps referring to the fact that the flush comes via a pipe from a separate tank, as distinct from the close-coupled WCs that are very common here in FR (in fact almost universal in modern installations)? If so, I'm not sure if there is a standard term or not, since in the UK this has traditionally been the 'normal' type, and we use 'close-coupled' for when it is not 'alimentation indépendante'.

You may need to look at some UK WC manufacturers and/or suppliers websites to find the description they use. I know I've come across 'high-level flush' and 'low-level flush' (tank mounted high up with chain flush / low tank with lever flush) and descriptions like 'washdown' and 'double-syphonic', but none of these is actually what you need!