XML Schema Sequence Question

[ChipR]

Is there any way to specify a sequence with one or more elements that can be repeated like

<complexType name="element_type">

<sequence>

<element name="A" type="string"/>
<element name="B" type="string" maxOccurs="10"/>
<element name="C" type="string"/>

</sequence>

</complexType>

but allow the elements to be in any order like all?

<all> only allows 0-1 of each element, but I don't want to require that the elements are in order as long as they are there, like AB+C, ACB+, B+AC, B+CA, CAB+, or CB+A

I just realized I could do a choice between all those sequences, which would be quite long in my complex schema, but is there a better way?

Thanks in advance,
Chip