Consider

<xs:complexType name="base">
  <xs:sequence>
    <xs:element name="dummy"/>
    <xs:element name="e" type="xs:string" fixed="abc" minOccurs="0"/>
  </xs:sequence>
</xs:complexType>

<xs:complexType name="restriction">
  <xs:complexContent>
    <xs:restriction bsae="base">
      <xs:sequence>
        <xs:element name="dummy"/>
      </xs:sequence>
    <xs:restriction>
  <xs:complexContent>
</xs:complexType>

<xs:complexType name="extension">
  <xs:complexContent>
    <xs:extension bsae="restriction">
      <xs:sequence>
        <xs:element name="e" type="xs:string" fixed="def" minOccurs="0"/>
      </xs:sequence>
    <xs:restriction>
  <xs:complexContent>
</xs:complexType>

Note the different "fixed" values.

Schema 1.0 has a rule like "all derivation can be done by doing all extensions first and restriction later". This makes the above invalid. Schema 1.1 plans to abandon this rule, which would allowed the above derivation. Should it be allowed?