Please note that Mommsen uses the AUC chronology (Ab Urbe Condita), i.e. from the founding of the City of Rome. You can use this reference table to have the B.C. dates
From: The History of Rome, by Theodor Mommsen
Translated with the sanction of the author by William Purdie Dickson
On the other hand it must have been at this period, when the indication and redaction of law began, that the Roman technical style first established itself--a style which at least in its developed shape is nowise inferior to the modern legal phraseology of England in stereotyped formulae and turns of expression, endless enumeration of particulars, and long-winded periods; and which commends itself to the initiated by its clearness and precision, while the layman who does not understand it listens, according to his character and humour, with reverence, impatience, or chagrin.
Moreover at this epoch began the treatment of the native languages after a rational method. About its commencement the Sabellian as well as the Latin idiom threatened, as we saw,(25) to become barbarous, and the abrasion of endings and the corruption of the vowels and more delicate consonants spread on all hands, just as was the case with the Romanic languages in the fifth and sixth centuries of the Christian era.
25. Cf. I. XIV. Corruption of Language and Writing
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Reference address : https://www.ellopos.net/elpenor/rome/2-09-art-science.asp?pg=28