In this test..

   <test-case name="cbcl-minus-023">
      <description> Test behaviour of minus operator when presented with an expression with static type duration </description>
      <created by="Oliver Hallam" on="2010-02-26"/>
      <dependency type="spec" value="XQ10+"/>
      
      <test>declare function local:f($x) { if ($x) then xs:duration("P1D") else xs:dayTimeDuration("P1H") }; local:f(false()) - xs:time("12:00:00")</test>
      <result>
         <error code="XPTY0004"/>
      </result>
   </test-case>

.."FORG0001" should be added, or the day time duration should be rewritten to xs:dayTimeDuration("PT1H").