Splinter -

3x=Singleton,
4x=Void

See Splinter for the basic Splinter bid.

In this variation, a triple jump shift shows a singleton in the suit bid while a quadruple jump shift shows a void.

Example:

1 4 shows a singleton in Diamonds, plus the usual extras in Hearts, and it forces to game.
1 5 shows a void in Diamonds. Since it forces opener to the 5 level, responder must have a little stronger hand and/or even more extras in Hearts.

Also see Random Splinters, which allow you to show voids below the game level (e.g.: 1-4) in response to 1 of a major.

Extra Trump for Minor Suit Jump Raises:

In response to 1 or 1, a splinter (as well as a limit raise) normally shows extra trump support. For example, a single raise just promises 3 of the major, but a limit raise or a splinter shows at least 4.

If this is applied to minors, where a single raise of Diamonds shows 4 (according to SAYC) and a single raise of Clubs shows 5, then limit raises and splinter raises should show at least 5 Diamonds or 6 Clubs.