WS-Policy example

Question

I would like to write a WS-Policy stating that there are two ways for delivering a hypothetical service: one requiring less bandwidth (first RMAssertion) and one requiring more bandwith (second RMAssertion). One of the two MUST be chosen (hence the ExactlyOne).

Did I express it correctly?

<wsp:Policy
  xmlns:wsp="http://www.w3.org/ns/ws-policy"
  xmlns:wsrmp="http://docs.oasis-open.org/ws-rx/wsrmp/200702"&gt;

  <wsp:ExactlyOne wsp:Usage="Required">
    <rmp:RMAssertion>
      <rmp:InactivityTimeout Milliseconds="600000" />
      <rmp:BaseRetransmissionInterval Milliseconds="3000" />
      <rmp:ExponentialBackoff />
      <rmp:AcknowledgementInterval Milliseconds="400" />
    </rmp:RMAssertion>

    <rmp:RMAssertion>
      <rmp:InactivityTimeout Milliseconds="600000" />
      <rmp:BaseRetransmissionInterval Milliseconds="1000" />
      <rmp:ExponentialBackoff />
      <rmp:AcknowledgementInterval Milliseconds="200" />
    </rmp:RMAssertion>
  </wsp:ExactlyOne>

</wsp:Policy>