[rerdavies]

In an asymmetrical design, the orientation of face carries no extra information, since orientation information is already carried by the orientation of the design on the back.

For decks with a symmetrical back design, the following cards have asymmetrical faces:

- The seven of diamonds.

- The ace, three, five, seven and nine of hearts, clubs and spades.

In my deck (a standard design), none of the face cards are asymmetrical.

So there are sixteen cards that carry orientation information, one of which must be used to define the reference orientation of the deck, yielding 15 additional bits of information.