This info can probably be found on site but bears repeating as Billy said. It also may have been updated.
ERROR CARDS: Wrongbacks, Wrongfronts, Blankbacks, Blankfronts, Miscuts - "usually" not listed or not considered a "true" error card.
STAMPED BUYBACKS: Listed only if stamped by original maker and reissued. NOT listed if stamped by an unlicensed 3rd party, not affiliated with original maker.
POCKET SCHEDULES: Must resemble a single trading card. Folded and serialized schedules are not allowed.