EDIT

<afp:AttributeFilterPolicyGroup

    xmlns="urn:mace:shibboleth:2.0:afp:mf:basic"

    xmlns:basic="urn:mace:shibboleth:2.0:afp:mf:basic"

    xmlns:afp="urn:mace:shibboleth:2.0:afp"

    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" >

    <afp:AttributeFilterPolicy>

        <!-- This policy is in effect in all cases. -->

        <afp:PolicyRequirementRule xsi:type="ANY"/>

        <!-- Catch-all that passes everything else through unmolested. -->

        <afp:AttributeRule attributeID="*">

            <afp:PermitValueRule xsi:type="ANY"/>

        </afp:AttributeRule>

    </afp:AttributeFilterPolicy>

</afp:AttributeFilterPolicyGroup>