[xml] XML Schema Help

["oknam park" <ponda7777 hotmail com>]

Hello All,

In the instance xml file, if I would like to allow different xsi-type and 
just free text like below,

<gemq:priceCode 
xsi:type="gemq:URI">http://www.purl.org/gem/instance/GEMpriceCode/free</gemq:priceCode>
<gemq:priceCode xsi:type="gemq:GEMPriceCode">Free</gemq:priceCode>
<gemq:priceCode>free</gemq:priceCode>

How could I need to change following gemq xml schema?

<xs:schema xmlns:gemq="http://purl.org/gem/qualifiers/"; 
xmlns:xs="http://www.w3.org/2001/XMLSchema"; 
targetNamespace="http://purl.org/gem/qualifiers/"; 
elementFormDefault="unqualified">
<xs:import namespace="http://www.w3.org/XML/1998/namespace"; 
schemaLocation="http://www.w3.org/2000/10/xml.xsd"/>

<xs:element name="priceCode"/>

<xs:simpleType name="URI">
  <xs:restriction base="xs:anyURI"/>
</xs:simpleType>
<xs:element name="GEMPriceCode">
<xs:simpleType>
   <xs:restriction base="xs:string">
      <xs:enumeration value="Free Based"/>
      <xs:enumeration value="Free"/>
      <xs:enumeration value="Partially Free"/>
   </xs:restriction>
</xs:simpleType>
</xs:element>

I treid to do in multiple ways, it keeps generating validation errors.

Could you do me a big favor?

Thanks a lot,

Best regards,
Oknam