DTD Element defintion help

[eswhite]

Hello,

How do I define an element so that it will only validate if it contains at least one or more child elements in any order?

Example:

<elt1><elt2/><elt3/></elt1>
<elt1><elt3/><elt2/></elt1>
<elt1><elt2/></elt1>
<elt1><elt3/></elt1>

would be the only valid uses.

I would rather not have to define element in DTD like this:

<!ELEMENT elt1 ((elt2, elt1) | (elt2, elt1) | (elt2) | (elt1))>

Thanks.