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
Lastly, it had already in the main become subsidiary law throughout the compass of the Roman empire, inasmuch as-- while the manifold local statutes were retained for those legal relations which were not directly commercial, as well as for local transactions between members of the same legal district--dealings relating to property between subjects of the empire belonging to different legal districts were regulated throughout after the model of the urban edict, though not applicable de jure to these cases, both in Italy and in the provinces.
The law of the urban edict had thus essentially the same position in that age which the Roman law has occupied in our political development; this also is, so far as such opposites can be combined, at once abstract and positive; this also recommended itself by its (compared with the earlier legal code) flexible forms of intercourse, and took its place by the side of the local statutes as universal subsidiary law. But the Roman legal development had an essential advantage over ours in this, that the denationalized legislation appeared not, as with us, prematurely and by artificial birth, but at the right time and agreeably to nature.
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Reference address : https://www.ellopos.net/elpenor/rome/5-11-old-republic-new-monarchy.asp?pg=172