Difficult to say, but AFAIK the French make their
doors just like ours. Perhaps you could e-mail or
write to the manufacturer? Babelfish translations
might be useful if you don't speak the language.

Oh Chris. I know, I know.
But EVERYONE calls them french doors, and if I ask a
question about "french windows" someone will say :
"Difficult to say, but AFAIK the French make their windows ..." (!)

The manufacturer is unknown - there were on a new-build house.

Simon.