Multiple element types in ng-transclude-slot?

Question

I'm doing multi-slot transclusion. My directive template (important bits):

<div>
  <div ng-transclude-slot='title'></div>
  <div ng-transclude-slot='body'></div>
</div>

Right now my transclude property in my directive definition looks like this:

transclude: {
  title: '?h1',
  body: '?div'
}

What if I want title to be able to take more than just <h1> elements though? Something like:

transclude: {
  title: '?h1?h2?h3',
  body: '?div'
}