 Marvel's major heroes were created in the 1960s, but the amount of time that has passed between then and now within the universe itself has (after a prolonged period of being identified as about 10 years in the mid-to-late 1990s) most recently been identified as 13 years.Consequently, the settings of some events which were contemporary when written have to be updated every few years to "make sense" in this floating timeline.Thus, the events of previous stories are considered to have happened within a certain number of years before the publishing date of the current issue.