 In 537, Justinian required that henceforth the date must include the name of the emperor and his regnal year, in addition to the indiction and the consul, while also allowing the use of local eras.In 309 and 310, and from time to time thereafter, no consuls were appointed.When this happened, the consular date was given a count of years since the last consul (so-called "post-consular" dating).