Jane,
"foundational text" works fine for my use case and was a perfect match for the semantics I was trying to capture.
"applies to territorial jurisdiction" is useful but not for my use. That property concept is a more specific way to say "involves".
X involves Y
NAFTA trade agreement INVOLVES North America
NAFTA trade agreement INVOLVES Canada, Mexico, USA
I notice that Wikidata authors and editors create many specific properties, but there very few generic properties, but probably for a good reason.....to avoid confusion. Regarding that... let me compose a new email forthcoming asking a question about that.