Natural Born citizen already has a definition, derived from Natural Law, well known to the founding fathers.
DoodleDawg asked:
Which is documented where?
From the article, quoting the supreme court (which is acknowledgement, if not documentation):
[O]ur law in this area follows English concepts with an acceptance of the jus soli, that is, that the place of birth governs citizenship status except as modified by statute
Breezed right by the "except as modified by statute" part I see. The Constitution gives Congress the power to enact uniform laws for naturalization. Part of that process has to be defining who must be naturalized and who are natural-born citizens. Cruz is a natural-born citizen.