Passing pattern value as parameter or reference dynamic - xsd

Question

I want to enforce my ID/IDRefs with a pattern. The code below works perfectly, but I would like to optimize it a bit, because all the different types are the same except for the first 3 characters in the pattern. Is it possible to have a generic type, which takes the prefix (SEG, ITI, ...) as a parameter ?
<xsd:complexType name="SegmentIDRefs">
<xsd:complexContent>
<xsd:restriction base="common:IDRefs">
<xsd:attribute name="Id">
<xsd:simpleType>
<xsd:restriction base="xsd:ID">
<xsd:pattern value="SEG_[\da-fA-F]{8}"/>
</xsd:restriction>
</xsd:simpleType>
</xsd:attribute>
<xsd:attribute name="GUID" type="common:external.GUID"/>
<xsd:attribute name="RefId">
<xsd:simpleType>
<xsd:restriction base="xsd:IDREF">
<xsd:pattern value="SEG_[\da-fA-F]{8}"/>
</xsd:restriction>
</xsd:simpleType>
</xsd:attribute>
</xsd:restriction>
</xsd:complexContent>
</xsd:complexType>
<xsd:complexType name="ItineraryIDRefs">
<xsd:complexContent>
<xsd:restriction base="common:IDRefs">
<xsd:attribute name="Id">
<xsd:simpleType>
<xsd:restriction base="xsd:ID">
<xsd:pattern value="ITI_[\da-fA-F]{8}"/>
</xsd:restriction>
</xsd:simpleType>
</xsd:attribute>
<xsd:attribute name="GUID" type="common:external.GUID"/>
<xsd:attribute name="RefId">
<xsd:simpleType>
<xsd:restriction base="xsd:IDREF">
<xsd:pattern value="ITI_[\da-fA-F]{8}"/>
</xsd:restriction>
</xsd:simpleType>
</xsd:attribute>
</xsd:restriction>
</xsd:complexContent>
</xsd:complexType>

Answer 1

Using XSD 1.1 you can use assertions to test the desired regex. This is not really a parametric type as it needs to base the regex on the name of the element.
Example (I've assumed that attributes are compulsory to simplify):
<!-- The ref type contains the attributes and an assertion to test the regex -->
<xsd:complexType name="myRefType">
<xsd:attribute name="Id" type="xsd:ID" use="required"/>
<xsd:attribute name="RefId" type="xsd:IDREF" use="required"/>
<xsd:attribute name="GUID" type="xsd:string"/>
<!-- Regex prefix is set based on node local name (it can be cahnged to use node first 3 letters if you want) -->
<xsd:assert test="let $regex:=(
concat(if (local-name()='itinerary') then 'ITI'
else if (local-name()='segment') then 'SEG'
else error(), '_[\da-fA-F]{8}'))
return matches(#Id, $regex) and matches(#RefId, $regex)"/>
</xsd:complexType>
<!-- Example root element containing an unbounded number of itinerary and semgent elements-->
<xsd:element name="root">
<xsd:complexType>
<xsd:sequence>
<xsd:element name="itinerary" type="common:myRefType" maxOccurs="unbounded"/>
<xsd:element name="segment" type="common:myRefType" maxOccurs="unbounded"/>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
This is not perfect but it is the best solution I was able to find.