Sometimes enemies are spaced out with empty space between them. According to what I can find on the SRD,
You can instead target a specific grid intersection. Treat this as a ranged attack against AC 5. However, if you target a grid intersection, creatures in all adjacent squares are dealt the splash damage, and the direct hit damage is not dealt to any creature.
But if you have monsters standing like so:
X| |X ----- |X|
Any given intersection can only hit 4 squares. If a monster had been standing between the two Xs, I could hit him for the direct damage, and hit all three other monsters with splash damage. Can I aim my splash weapon there, forgoing the direct damage to hit all three with splash?
Edit to add: I've just noticed that the sidebar on the d20pfsrd talking about what happens when you MISS with this attack has the following image:
If "T" means "Target", does that mean I actually target a square? Or is the image wrong? But if I only splash 4, how can I roll a d8 to determine which square I actually land in?