VOT XXX = vota trecennalia A sacred promise of victory for thirty years.

VICTORIA CONSTANTINI AUG(USTI), " The Victorious Emperor Constantine ".

SMNC is the abbreviation M.N. placed between the abbreviation S.C. S(enatus C(onsultus) = Issued on the authority of the Roman Senate, the fiction maintained by all the Roman Emperors that power resided in the senate. M(etalla aurarium) N(ova) = new gold mines, i.e., 'new gold issue'.

I have assumed here that XXX is 'trecennalia' although I cannot find such a word in the Oxford Latin Dictionary, or in any other Latin dictionary I have consulted. I have based the word on VOT XX (vota vicennalia) (from the Lexicon Abbreviaturarum of A. Capelli.) 'a sacred promise for twenty years'. The definition of vicennalis in the Oxford Latin Dictionary is 'made for twenty years' and gives the example VOTIS XX AUGG NN. If anyone can clarify VOT XXX further, please e-mail me.

7 April 2003. Additional Information.
Since writing the above I have found that the "XXX" does indeed signify a sacred promise of 30 years of victory. I have found a reference to this is in a document of AD 310, the Panegyrici Latini, 6(7).21.4-5, delivered at Tier before Constantine, which emphasised his reverence for Apollo (Sol Invictus).

"... For, O Constantine, you saw, I believe, your protector Apollo, in company with Victory, offering you laurel crowns, each of which bear the presage of XXX years. For this is the span of life which is owed to you, an age beyond that of Nestor."