[drc]

A means the card was not gradable (or the collector asked for A). It usually means the card is altered in some way or form.

For autographed cards, the collector may just be interested in the signature, so there gradable cards are more often given an A. Whether the card grades or a 5 or a 5.5 makes no different to the Mickey Mantle autograph collector.

In some cases, with rare and obscure issues-- like rare stamps-- the graders may not be sure exactly how to assign a grade, so give the A. Obviously, cut out cards (Wheaties, strip cards, etc) are tough to assign a grade.

But, in short, the majority of A-Authentic cards are altered.

Technically, an altered card is grade Poor.