Representation
Consider these five alternatives to the preceding diagram of a 4–4 fit.
The first alternative differs from the original in replacing each of the 5, 4, 3, and 2 by 'x', which conventionally represents the 2 or any other card low enough to be equivalent to the 2 for the purpose at hand. To determine which are those cards does require analysis that is challenging in some instances.
In bridge exposition, 'x' represents the 2 or any equivalent card in the same suit, whence it may be a great challenge to determine which cards 'x' represents in any specific diagram. Lacking such analysis 'x' nevertheless represents a card below any one that is specified. For example, the last of these five variations is equivalent to the original diagram because specification of the '5' implies that any unspecified 'x' is below the 5. The first variation is also equivalent to the original by convention. The middle three represent ♥A in declarer's hand with three cards below 8, three cards below 7, and three cards below 6 respectively. To say which of those diagrams is equivalent to the original, and whether they are equivalent to each other, demands analysis of the play.
(For standard analysis of suit combinations, the 7 is generally different from 'x' where the longer holding (traditionally dummy) is four cards and the defenders hold two high cards such as the king and ten in this case. The 7 is irrelevant if one hand holds QJ98, however, and the 8 is irrelevant if one hand holds AQJ9. Furthermore, when the defenders do hold at least 7 and two higher cards, the cards below 7 become important.)
| ♥ Q J 9 x x x |
| |
| ♥ A x x x x x |
(As presented here, a diagram may be inconsistent. In the last of these variations on the given combination, there are eight 'x' in the diagram, whose lowest specified card is 9, but a suit contains only seven cards below 9. Put another way, a 12-card combination is given, with the king and ten nominally missing, but there are only thirteen cards in a suit.)