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
The old Servian arrangement for voting in the centuriate comitia, under which the first class, with an estate of 100,000 sesterces (1000 pounds) or upwards, alone possessed almost half of the votes, again took the place of the arrangements introduced in 513 to mitigate the preponderance of the first class.(25)
25. Cf. III. XI. Reform of the Centuries
Practically there was thus introduced for the election of consuls, praetors, and censors, a census which really excluded the non-wealthy from exercising the suffrage. The legislative initiative in the case of the tribunes of the people was restricted by the rule, that every proposal had henceforth to be submitted by them in the first instance to the senate and could only come before the people in the event of the senate approving it.
These enactments which were called forth by the Sulpician attempt at revolution from the man who then came forward as the shield and sword of the constitutional party--the consul Sulla--bear an altogether peculiar character.
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Reference address : https://www.ellopos.net/elpenor/rome/4-07-sulpician-revolution.asp?pg=74