1♦ is our catchall opener. It is 10-15 HCP, could be 0 diamonds if 4=4=0=5 shape. If I have 6 or more diamonds, then I will have 13-15 HCP.
4♦ is a splinter for spades.
4♥ would be last train, 4N 1430. Partner's splinter is not really limited - its any hand which thinks slam is possible if diamond wastage isn't an issue, but which wants to kick it to me.
So clearly if you want to bid this scientifically you could bid 5♦...but do you want to bid this scientifically at matchpoints?