Combat Challenge and Immediate Actions

[Scribble]

So the fighter's Combat Challenge says this:

In addition, whenever a marked enemy that is
adjacent to you shifts or makes an attack that does not
include you, you can make a melee basic attack against
that enemy as an immediate interrupt.

So I assume it follows the normal rules of Immediate Actions right (ie one per round?)

 

[Kordeth]

Correct.