> What is really not elegant at all in XSLT 2.0 is the impossibility to
> define user data types inline in a stylesheet

But you can!

<xsl:stylesheet ...

<xsl:import-schema namespace="http://localhost/">
  <xs:schema targetNamespace="http://localhost">
    <xs:simpleType name="hatSize">
      <xs:restriction base="xs:unsignedInteger">
        <xs:maxInclusive value="10"/>
      </xs:restriction>
    </xs:simpleType>
  </xs:schema>
</xsl:import-schema>

<xsl:function name="my:measurements" as="my:hatSize">
  ...
</xsl:function>

</xsl:stylesheet>

Michael Kay
http://www.saxonica.com/