One almost needs to have an example in some detail to be able to answer that question. It's like a jigsaw puzzle. A commander in a coalition environment has to take all these different-shaped pieces of the jigsaw puzzle--those shapes being what each nation has put on in terms of caveats, what the capability of those forces are--and see what kind of picture he can create. In some cases, you don't need to get that complicated. In other cases, you have to be quite imaginative to be able to use the force, and then you have to really run the edges in terms of what those limitations are.
To my understanding--and I'm now perhaps straying a little bit--what's happening in Afghanistan is that the commander has taken British, Canadian, Dutch, and American forces and used them largely together, because their capability and the national caveats allow them pretty much to work together seamlessly. The others are in other areas doing other things where it's much less of a problem. That's a convenient way of doing it. The danger, of course, is that over time you actually do get a significantly disproportionate load on those nations that are doing the tough slogging. The question is, does that become a political issue for those nations?