Hah !, I see what you did there

Short answer:
The "nothing" referred to the ignoring of and not answering my questions posted 17 days earlier see
post 287.
My return, posted lest the gentle reader conclude I felt otherwise.
Longer answer:
A dealer was about pursuing answers.
Understood about standard units - and acknowledged in my preamble. The questions that followed asked to learn more about using (or choosing) the 50mm materials including the system used to construct them with.
Questions that I think it reasonable for the mfr to be able to answer. And, in my view not dissimilar to many others previously asked, and as a precedent, answered in this thread.
Indeed #2, about cutout placement limitations/recommendations, had been asked before - but that was for "84mm panels".
#1, about the interior height, was prompted by photos posted here with variations on the door placement relative to the floor and ceiling. Some with the lower or upper extrusion, or both, cut into. Some with a larger "header" etc. Of course those may have been earlier versions, one-offs, experimentations etc but somewhere in all that I'm thinking the mfr has determined a recommended min height, perhaps different than the one offered.
#3, on cap colour, was prompted by comments about dissimilar materials, different thermal expansion rates and covering panel with wraps.
Thanks again !