XML Schema

Hi,

I do not find a solution for my following problem:

The root elements of my XML data contain many different inner elements.
Therefore I chose a complexType definition for the root elements.

Some of the inner elements are only optional, others are included more than
one time (therefore I can not use "all" for the complexType).

I can not tell in which order the inner elements will appear. Therefore I
can not use "sequence" for the complexType.

I decided to use "choice" - with the attribute "maxOccurs" "unbounded" not
only allowing one element under the root elements.

But with that it seems I lose a validation opportunity to tell if an inner
element must appear or is only optional (minOccurs 1 for the inner elements
does not show a difference within validation).

Any idea how I could handle this situation?

Regards,
Udo