XRC (eXtended Rookie Card): Term used by Beckett to describe a rookie card from an extended or traded set. Because of the widespread distribution of extended sets, the XRC designation was discontinued after 1988.
Beckett however, grandfathered all existing XRCs, thus creating a rather confusing situation where a player can have his "rookie card" in a set AFTER his XRC was in a previous year's extended set.
For example: Barry Bonds's 1986 Fleer Update card is his first card and, had it been released just a few years later, would be his true rookie card. As it is, the '86 Fleer Update is considered by Beckett an "XRC," while Bonds's 1987 Fleer is given the "RC" label. General consensus in The Hobby is to treat BOTH cards as rookies.