How are era names determined?

Long ago, era names were changed not only upon the accession of a new emperor, following the death of his predecessor, but the name could also be changed during the reign of an emperor for such reasons as to ward off natural disasters or upon the succession of a new shogun to the bakufu government.
However, when the new era name for the Meiji period was established, it was determined that the emperor's reign and the era name would begin from the time of accession and continue until his death.
In the Japanese Constitution that came into force on May 3, 1947 following the end of the Pacific War, the emperor was made a "symbol of the state" but the provisions regarding imperial rule were left unchanged.
Until this time, era names had been decreed by the emperor; however, it is the cabinet that today determines era names.
When the accession of a new emperor is determined, the cabinet seeks proposals from various opinion leaders for a new era name, and selects one from among the proposals.
The era name "Heisei" was the first selected under this new system.