What you observed is part of the reasons because I think that
"indicazione estesa" or "oggetto esteso" would be the best choices:
despite the fact that these are two-word terms, they convey the exact
concept we need to describe, so if one tries to guess what they are,
chances are he gets the right meaning, in my opinion.
Furthermore, I think that they look technical enough to suggest to
read the manual.
So in the end I am convinced that they satisfy all the "requirements"
(accurate meaning, easy to guess, technical appearance) with the only
disadvantage of being two-word expressions.
I changed my mind also about the order of preference: I would choose
"indicazione estesa" and keep "oggetto esteso" as a substitution.