There are occasionally calls that are one level higher than necessary for a splinter and yet below game.
One example is the double jump reverse. For example:
In all four sequences, two of Opener's second suit would be forcing. Three of Opener's suit can operate as a splinter option. Thus, four of the suit is one higher than the minimum call needed for a splinter but still below game.
A second example would be a double jump cuebid below game.
I mention this merely because I saw a lot of posts recently where people bid four of a suit as a splinter, perhaps thinking that four of the suit sounds like a splinter, whereas in the sequence three of the suit would also sound like a splinter. When I mentioned this, some noted that three of the suit works and then opined as to what four of the suit should mean (void splinter? other?).
Personally, I think that if three of the suit is a splinter, then four of the suit should be a Picture Splinter of some variety (very well defined), because the call usually consumes a lot of space that would otherwise be available to unwind a lot of information. "Void Splinter" seems bad, if only because a void makes (1) slam more likely but (2) fine-tuning more important. Consider that with a void you might have much less other stuff to merit the splinter, but then you might also have a lot more stuff than the minimum void splinter requires. Accordingly, you have more need to unwind (it seems) with the void hands.