|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.