cipid: 

<display-name> (typo in the text also) can now have "xml:lang"
attribute, but the schema does not allow one, so a new schema should
e.g. be like:

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema targetNamespace="urn:ietf:params:xml:ns:pidf:cipid"
       xmlns:cipid="urn:ietf:params:xml:ns:pidf:cipid"
       xmlns:xs="http://www.w3.org/2001/XMLSchema"
       elementFormDefault="qualified"
       attributeFormDefault="unqualified">

    <xs:import namespace="http://www.w3.org/XML/1998/namespace"
       schemaLocation="http://www.w3.org/2001/xml.xsd"/>
 
    <xs:annotation>
       <xs:documentation>
         Describes CIPID tuple extensions for PIDF.
       </xs:documentation>
     </xs:annotation>

     <xs:element name="card" type="xs:anyURI"/>
     <xs:element name="display-name">
      <xs:complexType>
       <xs:simpleContent>
        <xs:extension base="xs:string">
         <xs:attribute ref="xml:lang"/>
        </xs:extension>
       </xs:simpleContent>
      </xs:complexType> 
     </xs:element>
     <xs:element name="homepage" type="xs:anyURI"/>
     <xs:element name="icon" type="xs:anyURI"/>
     <xs:element name="map" type="xs:anyURI"/>
     <xs:element name="sound" type="xs:anyURI"/>
</xs:schema>

Secondly, I'd much prefer if you also removed xmlns:xsi and
xsi:schemaLocation declarations from example instance documents, e.g.:

<?xml version="1.0" encoding="UTF-8"?>
<presence xmlns="urn:ietf:params:xml:ns:pidf"
    xmlns:dm="urn:ietf:params:xml:ns:pidf:data-model"
    xmlns:c="urn:ietf:params:xml:ns:pidf:cipid"
    entity="pres:someone@example.com">

     <tuple id="bs35r9">
       <status>
         <basic>open</basic>
       </status>
       <contact priority="0.8">im:alice@example.net</contact>
       <timestamp>2005-11-21T16:14:29Z</timestamp>
     </tuple>

     <dm:person id="p1">
       <c:card>http://example.com/~alice/card.vcd</c:card>
       <c:display-name>Alice Lewis</c:card>
       <c:homepage>http://example.com/~alice</c:homepage>
       <c:icon>http://example.com/~alice/me.png</c:icon>
       <c:map>http://example.com/~alice/gml-map.xml</c:map>
       <c:sound>http://example.com/~alice/hello.wav</c:sound>
       <dm:timestamp>2005-11-21T09:00:00+05:00</dm:timestamp>
     </dm:person>
</presence>