ballistic, the Tetra (a noun) is a derivative, like most Hebrew words, from a root verb (in this case hawah. This verb means, basically, "to be." As with all Hebrew verbs, the sense to be taken is either "perfect (as in a completed action)" or "imperfect (as in yet to be completed action)."
Considering God as infinite and dynamic, the "proper" sense would be the imperfect, hence the idea of "I shall prove to be," rather than "I am."
James Moffatt attempts to capture this thought when he translates the Tetra as "the Eternal."
Craig