Timezone ambiguities in date built-in type

Hi,

Given an XML document instance with time-zone, and a schema document without a time-zone – how should we validate facets such as maxExclusive?

Please consider the following example:

The time-zone in facet is not defined – can we claim that the instance is invalid, or should we deduce that since time-zone can’t be more than 14 hours, the XML instance is valid (since the year is smaller in the instance)?

<root MyAtt="1967-04-02Z"/>

<?xml version="1.0" ?>

<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema">

                <xsd:element name="root">

                    <xsd:complexType>

                                <xsd:attribute name="MyAtt">

                                    <xsd:simpleType>

                                                                <!-- begin restrictions -->

                                                                <xsd:restriction base="xsd:date">

                <xsd:maxExclusive value='1968-04-02'/>

                                                                <!-- end of restrictions -->

                                                                </xsd:restriction>

                                    </xsd:simpleType>

                                </xsd:attribute>

                    </xsd:complexType>

                </xsd:element>

</xsd:schema>