I've read the table which lists the various actions that do and do not provoke an AOO and know that an attack doesnt. But I'm unsure of what happens in the following situation.
If two PCs are threatening an enemy and this enemy attacks PC1, does PC2 get an AOO?
Logically speaking, attacking someone leaves you vulnerable to a second adjacent enemy. As far as I know the rules never clarify this situation. Or do they and have I just missed it completely?