 To be considered for induction by a screening committee, a player, retired coach, or referee must be fully retired from that role for at least three full seasons.The waiting period had originally been five years, but was changed to four years in December 2015, and to three seasons in December 2017.Prior to the induction class of 2018, referees had been eligible for induction after 25 years of full-time service, even if still active.