<?xml version="1.0" encoding="UTF-8"?>
<!-- Copyright 2007 XBRL International. All Rights Reserved.   
 
This version is non-normative - it should be identical to the normative version that is contained in Appendix A of the relevant specification except for this comment.

Following the schema maintenance policy of XBRL International, it is the intent (but is not guaranteed) that the location of non-normative versions of these schemas on the web will be as follows:

1)	While any schema is the most current RECOMMENDED version and until it is superseded by any additional errata corrections a non-normative version will reside on the web in the directory http://www.xbrl.org/2008/ - during the drafting process for this specification this directory should contain a copy of the most recent published version of the schema at http://www.xbrl.org/2008/period-filter.xsd.

2)	A non-normative version of each schema as corrected by any update to the RECOMMENDATION will be archived in perpetuity on the web in a directory that will contain a unique identification indicating the date of the update.

-->
<schema 
  targetNamespace="http://xbrl.org/2008/filter/period"
  elementFormDefault="qualified"
  xmlns="http://www.w3.org/2001/XMLSchema"
  xmlns:pf="http://xbrl.org/2008/filter/period" 
  xmlns:variable="http://xbrl.org/2008/variable" 
>

  <import namespace="http://www.xbrl.org/2003/XLink" 
    schemaLocation="http://www.xbrl.org/2003/xl-2003-12-31.xsd"/>

  <import namespace="http://xbrl.org/2008/variable" 
    schemaLocation="variable.xsd"/>

  <element id="xml-period-filter"
  name="period" substitutionGroup="variable:filter">
    <complexType mixed="true">
      <complexContent mixed="true">
        <extension base="variable:resource.type">
          <attribute name="test" type="variable:expression" use="required"/>
        </extension>
      </complexContent>
    </complexType>
  </element>

  <complexType name="date-time.model" mixed="true">
    <complexContent mixed="true">
      <extension base="variable:resource.type">
        <attribute name="date" type="variable:expression" use="required"/>
        <attribute name="time" type="variable:expression" use="optional"/>
      </extension>
    </complexContent>
  </complexType>
  
  <element id="xml-period-start-filter"
  name="periodStart"
  type="pf:date-time.model"
  substitutionGroup="variable:filter"/>

  <element  id="xml-period-end-filter"
  name="periodEnd"
  type="pf:date-time.model"
  substitutionGroup="variable:filter"/>

  <element id="xml-period-instant-filter"
  name="periodInstant"
  type="pf:date-time.model"
  substitutionGroup="variable:filter"/>

  <element id="xml-forever-filter"
  name="forever"
  substitutionGroup="variable:filter"
  type="variable:resource.type"/>

  <element id="xml-instant-duration-filter"
  name="instantDuration" substitutionGroup="variable:filter">
    <complexType mixed="true">
      <complexContent mixed="true">
        <extension base="variable:resource.type">
          <attribute name="variable" type="variable:QName" use="required"/>
          <attribute name="boundary" use="required">
            <simpleType>
              <restriction base="token">
                <enumeration value="start"/>
                <enumeration value="end"/>
              </restriction>
            </simpleType>
          </attribute>
        </extension>
      </complexContent>
    </complexType>
  </element>

</schema>
