<xs:element name="Document">
  <xs:annotation>
    <xs:documentation source="Gregor Hagedorn" xml:lang="en">Provides root element as long as terminology and descriptions must be in the same document!

The version of the SDD standard used is defined in the namespace declaration and needs no separate data element.</xs:documentation>
  </xs:annotation>
  <xs:complexType>
    <xs:sequence>
      <xs:element name="Generator">
        <xs:annotation>
          <xs:documentation source="Gregor Hagedorn" xml:lang="en">This information refers to the last process that created this document, which does not imply that the data have been authored there. The information is intended for debugging purposes, and to improve import quality if certain generator versions produce abnormal code.</xs:documentation>
        </xs:annotation>
        <xs:complexType>
          <xs:attribute name="Application" type="string255r" use="required"/>
          <xs:attribute name="Version" type="string255r" use="required"/>
          <xs:attribute name="Routine" type="string255r" use="optional">
            <xs:annotation>
              <xs:documentation source="Gregor Hagedorn" xml:lang="en">Optionally allows a generating application to identify which export routine created the document; some applications may have several alternative export routines.</xs:documentation>
            </xs:annotation>
          </xs:attribute>
          <xs:attribute name="Authors" type="string255r" use="optional">
            <xs:annotation>
              <xs:documentation source="Gregor Hagedorn" xml:lang="en">Identifies the authors of the generating application, not the authors of the terminology, descriptions, and resources!</xs:documentation>
            </xs:annotation>
          </xs:attribute>
          <xs:attribute name="Institution" type="string255r" use="optional"/>
          <xs:attribute name="Copyright" type="string255r" use="optional">
            <xs:annotation>
              <xs:documentation source="Gregor Hagedorn" xml:lang="en">This is the copyright string of the generating application, not the copyright of the terminology, descriptions, and resources!</xs:documentation>
            </xs:annotation>
          </xs:attribute>
          <xs:attribute name="LastUpdateDate" type="xs:date" use="required">
            <xs:annotation>
              <xs:documentation source="Gregor Hagedorn" xml:lang="en">The date on which the generating application actually updated (or, if no updates occurred, created) the current xml file.</xs:documentation>
            </xs:annotation>
          </xs:attribute>
        </xs:complexType>
      </xs:element>
      <xs:element name="ProjectDefinition" type="ProjectDefinitionType">
        <xs:annotation>
          <xs:documentation source="Gregor Hagedorn" xml:lang="en">Required information defining the project itself. Covering the entire document, i. e. terminology, descriptions, and resource collection.</xs:documentation>
        </xs:annotation>
      </xs:element>
      <xs:element name="Descriptions" type="DescriptionsType" minOccurs="0">
        <xs:annotation>
          <xs:documentation source="Gregor Hagedorn" xml:lang="en">Item descriptions are defined as 
optional to allow projects which
publish only terminology.</xs:documentation>
        </xs:annotation>
      </xs:element>
      <xs:element name="Terminology" type="TerminologyType"/>
      <xs:element name="ResourceDefinitions" type="ResourceDefinitionsType" minOccurs="0">
        <xs:annotation>
          <xs:documentation source="Gregor Hagedorn" xml:lang="en">Global resource definitions containing URIs or actually embedded resources (e. g. encoded images).</xs:documentation>
        </xs:annotation>
      </xs:element>
      <xs:element name="ApplicationData" minOccurs="0">
        <xs:annotation>
          <xs:documentation>Application specific information is placed in Processing Instructions. @@@DISCUSS: is this ok? Can PIs be easily parsed out by an application? @@@ Recommendation: Each application may read out its own information. Any other target information present should be preserved and output when a new document is generated. This is designed to support itempotent round tripping data between two applications. This implies that no dependency between the settings and the items and the terminology setting should be relied upon.</xs:documentation>
        </xs:annotation>
        <xs:complexType/>
      </xs:element>
    </xs:sequence>
  </xs:complexType>
  <xs:key name="AudienceDefinitionKey">
    <xs:selector xpath="./Terminology/AudienceDefinitions/AudienceDefinition"/>
    <xs:field xpath="@key"/>
  </xs:key>
  <xs:unique name="AudienceDefinitionUniqueLabel">
    <xs:annotation>
      <xs:documentation source="Gregor Hagedorn" xml:lang="en">The labels of audience definitions are required and must be unique for a given language ('lang' attribute).</xs:documentation>
    </xs:annotation>
    <xs:selector xpath="./Terminology/AudienceDefinitions/AudienceDefinition"/>
    <xs:field xpath="Label"/>
    <xs:field xpath="@lang"/>
  </xs:unique>
  <xs:key name="FrequencyDefinitionKey">
    <xs:selector xpath="./Terminology/FrequencyDefinitions/FrequencyDefinitionSet/FrequencyDefinition"/>
    <xs:field xpath="@key"/>
  </xs:key>
  <xs:unique name="FrequencyDefinitionUniqueLabel">
    <xs:annotation>
      <xs:documentation source="Gregor Hagedorn" xml:lang="en">The labels of frequency definitions are required and must be unique for a given audience definition (as defined through "keyref" attribute on LinguisticSet).</xs:documentation>
    </xs:annotation>
    <xs:selector xpath="./Terminology/FrequencyDefinitions/FrequencyDefinitionSet/FrequencyDefinition/LinguisticSets/LinguisticSet"/>
    <xs:field xpath="Label"/>
    <xs:field xpath="@keyref"/>
  </xs:unique>
  <xs:key name="ModifierDefinitionKey">
    <xs:selector xpath="./Terminology/ModifierDefinitions/ModifierDefinitionSet/ModifierDefinition"/>
    <xs:field xpath="@key"/>
  </xs:key>
  <xs:unique name="ModifierDefinitionUniqueLabel">
    <xs:annotation>
      <xs:documentation source="Gregor Hagedorn" xml:lang="en">The labels of modifier definitions are required and must be unique for a given audience definition (as defined through "keyref" attribute on LinguisticSet).</xs:documentation>
    </xs:annotation>
    <xs:selector xpath="./Terminology/ModifierDefinitions/ModifierDefinitionSet/ModifierDefinition/LinguisticSets/LinguisticSet"/>
    <xs:field xpath="Label"/>
    <xs:field xpath="@keyref"/>
  </xs:unique>
  <xs:key name="CharacterDefinitionKey">
    <xs:selector xpath="./Terminology/CharacterDefinitions/CharacterDefinition"/>
    <xs:field xpath="@key"/>
  </xs:key>
  <xs:unique name="CharacterDefinitionUniqueLabel">
    <xs:annotation>
      <xs:documentation source="Gregor Hagedorn" xml:lang="en">The labels of character definitions are required and must be unique for a given audience definition (as defined through "keyref" attribute on LinguisticSet).</xs:documentation>
    </xs:annotation>
    <xs:selector xpath="./Terminology/CharacterDefinitions/CharacterDefinition/LinguisticSets/LinguisticSet"/>
    <xs:field xpath="Label"/>
    <xs:field xpath="@keyref"/>
  </xs:unique>
  <xs:key name="CharacterGroupItemKey">
    <xs:annotation>
      <xs:documentation source="Gregor Hagedorn" xml:lang="en">The following xpath selects all CharacterGroupItem anywhere in the document. This is in fact more general and therefore computation intensive than necessary, a better xpath expression would be ./Terminology/CharacterGroupDefinitions/CharacterGroupDefinition//CharacterGroupItem. It should include all item nodes, regardless of their place in the tree structure. However, combining a defined path with an "all child" path seems to be not possible under the restrictions imposed on xpath expressions in xml-schema identity constraints. </xs:documentation>
    </xs:annotation>
    <xs:selector xpath=".//CharacterGroupItem"/>
    <xs:field xpath="@key"/>
  </xs:key>
  <xs:key name="CharacterGroupDefinitionKey">
    <xs:selector xpath="./Terminology/CharacterGroupDefinitions/CharacterGroupDefinition"/>
    <xs:field xpath="@key"/>
  </xs:key>
  <xs:unique name="CharacterGroupDefinitionUniqueLabel">
    <xs:annotation>
      <xs:documentation source="Gregor Hagedorn" xml:lang="en">The labels of character group definitions are required and must be unique for a given audience definition (as defined through "keyref" attribute on LinguisticSet).</xs:documentation>
    </xs:annotation>
    <xs:selector xpath="./Terminology/CharacterGroupDefinitions/CharacterGroupDefinition/LinguisticSets/LinguisticSet"/>
    <xs:field xpath="Label"/>
    <xs:field xpath="@keyref"/>
  </xs:unique>
  <xs:key name="CharacterStateDefinitionKey">
    <xs:selector xpath="./Terminology/CharacterDefinitions/CharacterDefinition/StateDefinitions/LocalStateDefinition/StateDefinition"/>
    <xs:field xpath="@key"/>
  </xs:key>
  <xs:unique name="CharacterStateUniqueLabel">
    <xs:annotation>
      <xs:documentation source="Gregor Hagedorn" xml:lang="en">The labels of character state definitions are required to be unique within each character and audience definition. This is tested by testing global uniqueness in combination with the unique character label. @@@NOTE: THIS DOES NOT WORK PROPERLY YET!@@@</xs:documentation>
    </xs:annotation>
    <xs:selector xpath="./Terminology/CharacterDefinitions/CharacterDefinition"/>
    <xs:field xpath="Label"/>
    <xs:field xpath="StateDefinitions/LocalStateDefinition/StateDefinition/LinguisticSets/LinguisticSet/Label"/>
    <xs:field xpath="StateDefinitions/LocalStateDefinition/StateDefinition/LinguisticSets/LinguisticSet/@keyref"/>
  </xs:unique>
  <!-- The place of key definition defines not only the starting point for the xpath, but also its scope/validity. While keyref can be defined with the element, keyrefs must be at the root to be visible by all keyrefs. The document root is the branching point for terminology and description. -->
</xs:element>

<xs:element name="Generator">
  <xs:annotation>
    <xs:documentation source="Gregor Hagedorn" xml:lang="en">This information refers to the last process that created this document, which does not imply that the data have been authored there. The information is intended for debugging purposes, and to improve import quality if certain generator versions produce abnormal code.</xs:documentation>
  </xs:annotation>
  <xs:complexType>
    <xs:attribute name="Application" type="string255r" use="required"/>
    <xs:attribute name="Version" type="string255r" use="required"/>
    <xs:attribute name="Routine" type="string255r" use="optional">
      <xs:annotation>
        <xs:documentation source="Gregor Hagedorn" xml:lang="en">Optionally allows a generating application to identify which export routine created the document; some applications may have several alternative export routines.</xs:documentation>
      </xs:annotation>
    </xs:attribute>
    <xs:attribute name="Authors" type="string255r" use="optional">
      <xs:annotation>
        <xs:documentation source="Gregor Hagedorn" xml:lang="en">Identifies the authors of the generating application, not the authors of the terminology, descriptions, and resources!</xs:documentation>
      </xs:annotation>
    </xs:attribute>
    <xs:attribute name="Institution" type="string255r" use="optional"/>
    <xs:attribute name="Copyright" type="string255r" use="optional">
      <xs:annotation>
        <xs:documentation source="Gregor Hagedorn" xml:lang="en">This is the copyright string of the generating application, not the copyright of the terminology, descriptions, and resources!</xs:documentation>
      </xs:annotation>
    </xs:attribute>
    <xs:attribute name="LastUpdateDate" type="xs:date" use="required">
      <xs:annotation>
        <xs:documentation source="Gregor Hagedorn" xml:lang="en">The date on which the generating application actually updated (or, if no updates occurred, created) the current xml file.</xs:documentation>
      </xs:annotation>
    </xs:attribute>
  </xs:complexType>
</xs:element>

<xs:element name="ProjectDefinition" type="ProjectDefinitionType">
  <xs:annotation>
    <xs:documentation source="Gregor Hagedorn" xml:lang="en">Required information defining the project itself. Covering the entire document, i. e. terminology, descriptions, and resource collection.</xs:documentation>
  </xs:annotation>
</xs:element>

<xs:element name="Descriptions" type="DescriptionsType" minOccurs="0">
  <xs:annotation>
    <xs:documentation source="Gregor Hagedorn" xml:lang="en">Item descriptions are defined as 
optional to allow projects which
publish only terminology.</xs:documentation>
  </xs:annotation>
</xs:element>

<xs:element name="Terminology" type="TerminologyType"/>

<xs:element name="ResourceDefinitions" type="ResourceDefinitionsType" minOccurs="0">
  <xs:annotation>
    <xs:documentation source="Gregor Hagedorn" xml:lang="en">Global resource definitions containing URIs or actually embedded resources (e. g. encoded images).</xs:documentation>
  </xs:annotation>
</xs:element>

<xs:element name="ApplicationData" minOccurs="0">
  <xs:annotation>
    <xs:documentation>Application specific information is placed in Processing Instructions. @@@DISCUSS: is this ok? Can PIs be easily parsed out by an application? @@@ Recommendation: Each application may read out its own information. Any other target information present should be preserved and output when a new document is generated. This is designed to support itempotent round tripping data between two applications. This implies that no dependency between the settings and the items and the terminology setting should be relied upon.</xs:documentation>
  </xs:annotation>
  <xs:complexType/>
</xs:element>

<xs:complexType name="CharacterDefinitionType">
  <xs:annotation>
    <xs:documentation source="Gregor Hagedorn" xml:lang="en">Defines a character in the terminology</xs:documentation>
  </xs:annotation>
  <xs:sequence>
    <xs:element name="LinguisticSets" type="LinguisticSets.ExtendedLabelType">
      <xs:annotation>
        <xs:documentation>Note on LinguisticSet contents: Character labels should be unique within the entire CharacterDefinitions collection (separately for each audience definition).</xs:documentation>
      </xs:annotation>
    </xs:element>
    <xs:element name="DescriptorDefinitions">
      <xs:annotation>
        <xs:documentation>At least a single descriptor must be present (@@@ currently not implemented in the schema! @@@)</xs:documentation>
      </xs:annotation>
      <xs:complexType>
        <xs:sequence>
          <xs:element name="GlobalStateSetReference" minOccurs="0" maxOccurs="unbounded">
            <xs:annotation>
              <xs:documentation>Optionally globally defined state sets may be referenced and thus defined for a character. In general at least the special states should be referenced here.</xs:documentation>
            </xs:annotation>
            <xs:complexType>
              <xs:sequence>
                <xs:element name="Selections" minOccurs="0">
                  <xs:annotation>
                    <xs:documentation source="Gregor Hagedorn" xml:lang="en">If Selections is missing, all descriptor states will be included, else only the selected ones.</xs:documentation>
                  </xs:annotation>
                  <xs:complexType>
                    <xs:sequence>
                      <xs:element name="DescriptorSelection" maxOccurs="unbounded">
                        <xs:complexType>
                          <xs:attribute name="keyref" use="required"/>
                        </xs:complexType>
                      </xs:element>
                    </xs:sequence>
                  </xs:complexType>
                </xs:element>
              </xs:sequence>
              <xs:attribute name="keyref" use="required"/>
            </xs:complexType>
          </xs:element>
          <xs:element name="LocalStateDefinitions" minOccurs="0">
            <xs:complexType>
              <xs:sequence>
                <xs:element name="StateDefinition" type="CharacterStateDefinitionType" maxOccurs="unbounded"/>
              </xs:sequence>
            </xs:complexType>
          </xs:element>
          <xs:element name="MeasureDefinitions" minOccurs="0">
            <xs:annotation>
              <xs:documentation>These definitions constrain which global measure definitions can appear in items of this character.</xs:documentation>
            </xs:annotation>
            <xs:complexType>
              <xs:sequence>
                <xs:element name="MeasurementUnit" minOccurs="0">
                  <xs:annotation>
                    <xs:documentation source="Gregor Hagedorn" xml:lang="en">Unit like mm, µm, °C. Attributes allow to output before value (e.g. pH 7.0) or without blank. The content allows some xhtml formatting to support "mm <sup>2</sup>".</xs:documentation>
                  </xs:annotation>
                  <xs:complexType>
                    <xs:complexContent>
                      <xs:extension base="FormattedSimpleTextType">
                        <xs:attribute name="Postfix" type="xs:boolean" use="optional" default="true"/>
                        <xs:attribute name="AddBlank" type="xs:boolean" use="optional" default="true"/>
                      </xs:extension>
                    </xs:complexContent>
                  </xs:complexType>
                </xs:element>
                <xs:element name="MeasureDefinition" maxOccurs="unbounded">
                  <xs:annotation>
                    <xs:documentation source="Gregor Hagedorn" xml:lang="en">The key attribute must be unique and is referred to in the item descriptions. The keyref refers to the measure semantics defined in the global measure definitions.</xs:documentation>
                  </xs:annotation>
                  <xs:complexType>
                    <xs:attribute name="key" type="string255r" use="required"/>
                    <xs:attribute name="keyref" use="required"/>
                  </xs:complexType>
                </xs:element>
              </xs:sequence>
            </xs:complexType>
          </xs:element>
        </xs:sequence>
      </xs:complexType>
    </xs:element>
    <xs:element name="FrequencyModifierSelections" minOccurs="0">
      <xs:annotation>
        <xs:documentation>(@@@PLACEHOLDER!@@@) Enabling of 0-n single frequency modifiers or 0-n frequency modifier sets for all states in a character.</xs:documentation>
      </xs:annotation>
      <xs:complexType/>
    </xs:element>
    <xs:element name="ModifierSelections" minOccurs="0">
      <xs:annotation>
        <xs:documentation>(@@@PLACEHOLDER!@@@) Enabling of 0-n single modifiers or 0-n modifier sets for all states in a character.</xs:documentation>
      </xs:annotation>
      <xs:complexType/>
    </xs:element>
    <xs:element name="Resources" type="ResourceReferencesType" minOccurs="0"/>
  </xs:sequence>
  <xs:attribute name="key" type="string255r" use="required"/>
  <xs:attribute name="type" use="optional" default="nominal">
    <xs:simpleType>
      <xs:restriction base="xs:NMTOKEN">
        <xs:enumeration value="nominal"/>
        <xs:enumeration value="ordinal-discrete"/>
        <xs:enumeration value="ordinal-interval"/>
      </xs:restriction>
    </xs:simpleType>
  </xs:attribute>
</xs:complexType>

<xs:element name="LinguisticSets" type="LinguisticSets.ExtendedLabelType">
  <xs:annotation>
    <xs:documentation>Note on LinguisticSet contents: Character labels should be unique within the entire CharacterDefinitions collection (separately for each audience definition).</xs:documentation>
  </xs:annotation>
</xs:element>

<xs:element name="DescriptorDefinitions">
  <xs:annotation>
    <xs:documentation>At least a single descriptor must be present (@@@ currently not implemented in the schema! @@@)</xs:documentation>
  </xs:annotation>
  <xs:complexType>
    <xs:sequence>
      <xs:element name="GlobalStateSetReference" minOccurs="0" maxOccurs="unbounded">
        <xs:annotation>
          <xs:documentation>Optionally globally defined state sets may be referenced and thus defined for a character. In general at least the special states should be referenced here.</xs:documentation>
        </xs:annotation>
        <xs:complexType>
          <xs:sequence>
            <xs:element name="Selections" minOccurs="0">
              <xs:annotation>
                <xs:documentation source="Gregor Hagedorn" xml:lang="en">If Selections is missing, all descriptor states will be included, else only the selected ones.</xs:documentation>
              </xs:annotation>
              <xs:complexType>
                <xs:sequence>
                  <xs:element name="DescriptorSelection" maxOccurs="unbounded">
                    <xs:complexType>
                      <xs:attribute name="keyref" use="required"/>
                    </xs:complexType>
                  </xs:element>
                </xs:sequence>
              </xs:complexType>
            </xs:element>
          </xs:sequence>
          <xs:attribute name="keyref" use="required"/>
        </xs:complexType>
      </xs:element>
      <xs:element name="LocalStateDefinitions" minOccurs="0">
        <xs:complexType>
          <xs:sequence>
            <xs:element name="StateDefinition" type="CharacterStateDefinitionType" maxOccurs="unbounded"/>
          </xs:sequence>
        </xs:complexType>
      </xs:element>
      <xs:element name="MeasureDefinitions" minOccurs="0">
        <xs:annotation>
          <xs:documentation>These definitions constrain which global measure definitions can appear in items of this character.</xs:documentation>
        </xs:annotation>
        <xs:complexType>
          <xs:sequence>
            <xs:element name="MeasurementUnit" minOccurs="0">
              <xs:annotation>
                <xs:documentation source="Gregor Hagedorn" xml:lang="en">Unit like mm, µm, °C. Attributes allow to output before value (e.g. pH 7.0) or without blank. The content allows some xhtml formatting to support "mm <sup>2</sup>".</xs:documentation>
              </xs:annotation>
              <xs:complexType>
                <xs:complexContent>
                  <xs:extension base="FormattedSimpleTextType">
                    <xs:attribute name="Postfix" type="xs:boolean" use="optional" default="true"/>
                    <xs:attribute name="AddBlank" type="xs:boolean" use="optional" default="true"/>
                  </xs:extension>
                </xs:complexContent>
              </xs:complexType>
            </xs:element>
            <xs:element name="MeasureDefinition" maxOccurs="unbounded">
              <xs:annotation>
                <xs:documentation source="Gregor Hagedorn" xml:lang="en">The key attribute must be unique and is referred to in the item descriptions. The keyref refers to the measure semantics defined in the global measure definitions.</xs:documentation>
              </xs:annotation>
              <xs:complexType>
                <xs:attribute name="key" type="string255r" use="required"/>
                <xs:attribute name="keyref" use="required"/>
              </xs:complexType>
            </xs:element>
          </xs:sequence>
        </xs:complexType>
      </xs:element>
    </xs:sequence>
  </xs:complexType>
</xs:element>

<xs:element name="GlobalStateSetReference" minOccurs="0" maxOccurs="unbounded">
  <xs:annotation>
    <xs:documentation>Optionally globally defined state sets may be referenced and thus defined for a character. In general at least the special states should be referenced here.</xs:documentation>
  </xs:annotation>
  <xs:complexType>
    <xs:sequence>
      <xs:element name="Selections" minOccurs="0">
        <xs:annotation>
          <xs:documentation source="Gregor Hagedorn" xml:lang="en">If Selections is missing, all descriptor states will be included, else only the selected ones.</xs:documentation>
        </xs:annotation>
        <xs:complexType>
          <xs:sequence>
            <xs:element name="DescriptorSelection" maxOccurs="unbounded">
              <xs:complexType>
                <xs:attribute name="keyref" use="required"/>
              </xs:complexType>
            </xs:element>
          </xs:sequence>
        </xs:complexType>
      </xs:element>
    </xs:sequence>
    <xs:attribute name="keyref" use="required"/>
  </xs:complexType>
</xs:element>

<xs:element name="Selections" minOccurs="0">
  <xs:annotation>
    <xs:documentation source="Gregor Hagedorn" xml:lang="en">If Selections is missing, all descriptor states will be included, else only the selected ones.</xs:documentation>
  </xs:annotation>
  <xs:complexType>
    <xs:sequence>
      <xs:element name="DescriptorSelection" maxOccurs="unbounded">
        <xs:complexType>
          <xs:attribute name="keyref" use="required"/>
        </xs:complexType>
      </xs:element>
    </xs:sequence>
  </xs:complexType>
</xs:element>

<xs:element name="DescriptorSelection" maxOccurs="unbounded">
  <xs:complexType>
    <xs:attribute name="keyref" use="required"/>
  </xs:complexType>
</xs:element>

<xs:element name="LocalStateDefinitions" minOccurs="0">
  <xs:complexType>
    <xs:sequence>
      <xs:element name="StateDefinition" type="CharacterStateDefinitionType" maxOccurs="unbounded"/>
    </xs:sequence>
  </xs:complexType>
</xs:element>

<xs:element name="StateDefinition" type="CharacterStateDefinitionType" maxOccurs="unbounded"/>

<xs:element name="MeasureDefinitions" minOccurs="0">
  <xs:annotation>
    <xs:documentation>These definitions constrain which global measure definitions can appear in items of this character.</xs:documentation>
  </xs:annotation>
  <xs:complexType>
    <xs:sequence>
      <xs:element name="MeasurementUnit" minOccurs="0">
        <xs:annotation>
          <xs:documentation source="Gregor Hagedorn" xml:lang="en">Unit like mm, µm, °C. Attributes allow to output before value (e.g. pH 7.0) or without blank. The content allows some xhtml formatting to support "mm <sup>2</sup>".</xs:documentation>
        </xs:annotation>
        <xs:complexType>
          <xs:complexContent>
            <xs:extension base="FormattedSimpleTextType">
              <xs:attribute name="Postfix" type="xs:boolean" use="optional" default="true"/>
              <xs:attribute name="AddBlank" type="xs:boolean" use="optional" default="true"/>
            </xs:extension>
          </xs:complexContent>
        </xs:complexType>
      </xs:element>
      <xs:element name="MeasureDefinition" maxOccurs="unbounded">
        <xs:annotation>
          <xs:documentation source="Gregor Hagedorn" xml:lang="en">The key attribute must be unique and is referred to in the item descriptions. The keyref refers to the measure semantics defined in the global measure definitions.</xs:documentation>
        </xs:annotation>
        <xs:complexType>
          <xs:attribute name="key" type="string255r" use="required"/>
          <xs:attribute name="keyref" use="required"/>
        </xs:complexType>
      </xs:element>
    </xs:sequence>
  </xs:complexType>
</xs:element>

<xs:element name="MeasurementUnit" minOccurs="0">
  <xs:annotation>
    <xs:documentation source="Gregor Hagedorn" xml:lang="en">Unit like mm, µm, °C. Attributes allow to output before value (e.g. pH 7.0) or without blank. The content allows some xhtml formatting to support "mm <sup>2</sup>".</xs:documentation>
  </xs:annotation>
  <xs:complexType>
    <xs:complexContent>
      <xs:extension base="FormattedSimpleTextType">
        <xs:attribute name="Postfix" type="xs:boolean" use="optional" default="true"/>
        <xs:attribute name="AddBlank" type="xs:boolean" use="optional" default="true"/>
      </xs:extension>
    </xs:complexContent>
  </xs:complexType>
</xs:element>

<xs:element name="MeasureDefinition" maxOccurs="unbounded">
  <xs:annotation>
    <xs:documentation source="Gregor Hagedorn" xml:lang="en">The key attribute must be unique and is referred to in the item descriptions. The keyref refers to the measure semantics defined in the global measure definitions.</xs:documentation>
  </xs:annotation>
  <xs:complexType>
    <xs:attribute name="key" type="string255r" use="required"/>
    <xs:attribute name="keyref" use="required"/>
  </xs:complexType>
</xs:element>

<xs:element name="FrequencyModifierSelections" minOccurs="0">
  <xs:annotation>
    <xs:documentation>(@@@PLACEHOLDER!@@@) Enabling of 0-n single frequency modifiers or 0-n frequency modifier sets for all states in a character.</xs:documentation>
  </xs:annotation>
  <xs:complexType/>
</xs:element>

<xs:element name="ModifierSelections" minOccurs="0">
  <xs:annotation>
    <xs:documentation>(@@@PLACEHOLDER!@@@) Enabling of 0-n single modifiers or 0-n modifier sets for all states in a character.</xs:documentation>
  </xs:annotation>
  <xs:complexType/>
</xs:element>

<xs:element name="Resources" type="ResourceReferencesType" minOccurs="0"/>

<xs:complexType name="CharacterGroupDefinitionType">
  <xs:annotation>
    <xs:documentation source="Gregor Hagedorn" xml:lang="en">Defines an entire character group (flat list or tree hierarchy)</xs:documentation>
  </xs:annotation>
  <xs:sequence>
    <xs:element name="LinguisticSets" type="LinguisticSets.ExtendedLabelType">
      <xs:annotation>
        <xs:documentation source="Gregor Hagedorn" xml:lang="en">Defines label displayed when a grouping is selected in the user interface</xs:documentation>
      </xs:annotation>
    </xs:element>
    <xs:element name="Purposes" minOccurs="0">
      <xs:annotation>
        <xs:documentation source="Gregor Hagedorn" xml:lang="en">Purposes are standardized to simplify application interoperability.</xs:documentation>
      </xs:annotation>
      <xs:complexType>
        <xs:sequence>
          <xs:element name="Purpose" maxOccurs="unbounded">
            <xs:complexType>
              <xs:attribute name="name" use="required">
                <xs:simpleType>
                  <xs:restriction base="xs:NMTOKEN">
                    <xs:enumeration value="DefaultGeneral">
                      <xs:annotation>
                        <xs:documentation source="Gregor Hagedorn" xml:lang="en">Setting this purpose in a character grouping is a recommendation to applications with a user interface to use this as the default hierarchy for any editing or reporting purpose. The application may, however, enable the user to select any character grouping.</xs:documentation>
                      </xs:annotation>
                    </xs:enumeration>
                    <xs:enumeration value="DefaultDescriptionEditorView">
                      <xs:annotation>
                        <xs:documentation source="Gregor Hagedorn" xml:lang="en">Setting this purpose in a character grouping is a recommendation to applications with a user interface to use this as the default hierarchy for editing the item description data set. The application may, however, enable the user to select any character grouping.</xs:documentation>
                      </xs:annotation>
                    </xs:enumeration>
                    <xs:enumeration value="DefaultTerminologyEditorView">
                      <xs:annotation>
                        <xs:documentation source="Gregor Hagedorn" xml:lang="en">Setting this purpose in a character grouping is a recommendation to applications with a user interface to use this as the default hierarchy for editing the terminology. The application may, however, enable the user to select any character grouping.</xs:documentation>
                      </xs:annotation>
                    </xs:enumeration>
                    <xs:enumeration value="GuidedKeyBuilder">
                      <xs:annotation>
                        <xs:documentation source="Gregor Hagedorn" xml:lang="en">Setting this purpose in a character grouping is a recommendation to applications to use this as the default hierarchy for building guided keys (e. g. dichotomous keys).</xs:documentation>
                      </xs:annotation>
                    </xs:enumeration>
                    <xs:enumeration value="InteractiveIdentification">
                      <xs:annotation>
                        <xs:documentation source="Gregor Hagedorn" xml:lang="en">Setting this purpose in a character grouping is a recommendation to applications to use this as the default hierarchy for interactive identification.</xs:documentation>
                      </xs:annotation>
                    </xs:enumeration>
                    <xs:enumeration value="NaturalLanguageReporting">
                      <xs:annotation>
                        <xs:documentation source="Gregor Hagedorn" xml:lang="en">Setting this purpose in a character grouping is a recommendation to applications to use this as the default hierarchy for natural language reporting.</xs:documentation>
                      </xs:annotation>
                    </xs:enumeration>
                  </xs:restriction>
                </xs:simpleType>
              </xs:attribute>
            </xs:complexType>
          </xs:element>
        </xs:sequence>
      </xs:complexType>
    </xs:element>
    <xs:element name="CharacterGroupItem" type="CharacterGroupItemType" maxOccurs="unbounded"/>
  </xs:sequence>
  <xs:attribute name="key" type="string255r" use="required"/>
  <xs:attribute name="MinimumExpertiseLevel" type="ExpertiseLevelType" use="optional" default="1">
    <xs:annotation>
      <xs:documentation>MinimumExpertiseLevel: the designer of the subset expects the user to have a  certain minimum expertise level. @@@ Needs discussion! @@@</xs:documentation>
    </xs:annotation>
  </xs:attribute>
  <xs:attribute name="complete" type="xs:boolean" use="optional" default="false">
    <xs:annotation>
      <xs:documentation source="Gregor Hagedorn" xml:lang="en">The designer of a character grouping defines it as 'complete' to declare that it is intended to include all characters of the terminology. A terminology editing application can use this information e. g. to warn the designer about missing characters, to display special dialog boxes after the creation of a new character, etc.</xs:documentation>
    </xs:annotation>
  </xs:attribute>
  <xs:attribute name="type" use="required">
    <xs:annotation>
      <xs:documentation source="Gregor Hagedorn" xml:lang="en">This attribute is currently not used, instead the key of the StateSet has been fixed for special states to SpecialStates. Needs discussion!</xs:documentation>
    </xs:annotation>
    <xs:simpleType>
      <xs:restriction base="xs:NMTOKEN">
        <xs:enumeration value="BasicPropertyTypes">
          <xs:annotation>
            <xs:documentation source="Gregor Hagedorn" xml:lang="en">Categorizing characters into basic property types (e. g. color, 2-dim. shape, 3-dim. shape, surface texture, taste, smell, behaviour, physiology, measurements, etc.) greatly improves the analysis and management of larger character sets and is therefore recommended. Note: Only a single character grouping should have this hierarchy type. (not enforced in schema, how can it be enforced? Other types occur multiple, i. e. one cannot make a UNIQUE statement on attribute!</xs:documentation>
          </xs:annotation>
        </xs:enumeration>
        <xs:enumeration value="ObservationMethodHierarchy">
          <xs:annotation>
            <xs:documentation source="Gregor Hagedorn" xml:lang="en">A hierarchy that organizes characters by method, e.g. field observation, light microscopy, electron microscopy, molecular methods, culture techniques, etc.</xs:documentation>
          </xs:annotation>
        </xs:enumeration>
        <xs:enumeration value="PartHierarchy">
          <xs:annotation>
            <xs:documentation source="Gregor Hagedorn" xml:lang="en">A hierarchy that organizes characters by a morphological "contains" hierarchy: plant = root/stem/leaf, leaf = base/stipules/petiole/lamina, etc.</xs:documentation>
          </xs:annotation>
        </xs:enumeration>
        <xs:enumeration value="FlatSubsets">
          <xs:annotation>
            <xs:documentation source="Gregor Hagedorn" xml:lang="en">Defining a grouping as flat subset marks it as being intended only for filtering purposes and prevents it from being displayed as a choice for a hierarchy in a user interface. Note that conversely, the filter selection dialog should not be restricted to these groupings. Any character grouping, including part, method or basic property type hierarchies are valuable filters defining character subsets.</xs:documentation>
          </xs:annotation>
        </xs:enumeration>
        <xs:enumeration value="UserDefinedHierarchy">
          <xs:annotation>
            <xs:documentation source="Gregor Hagedorn" xml:lang="en">used for character groupings that fall into none of the categories above.</xs:documentation>
          </xs:annotation>
        </xs:enumeration>
        <xs:enumeration value="CharacterArray"/>
      </xs:restriction>
    </xs:simpleType>
  </xs:attribute>
</xs:complexType>

<xs:element name="LinguisticSets" type="LinguisticSets.ExtendedLabelType">
  <xs:annotation>
    <xs:documentation source="Gregor Hagedorn" xml:lang="en">Defines label displayed when a grouping is selected in the user interface</xs:documentation>
  </xs:annotation>
</xs:element>

<xs:element name="Purposes" minOccurs="0">
  <xs:annotation>
    <xs:documentation source="Gregor Hagedorn" xml:lang="en">Purposes are standardized to simplify application interoperability.</xs:documentation>
  </xs:annotation>
  <xs:complexType>
    <xs:sequence>
      <xs:element name="Purpose" maxOccurs="unbounded">
        <xs:complexType>
          <xs:attribute name="name" use="required">
            <xs:simpleType>
              <xs:restriction base="xs:NMTOKEN">
                <xs:enumeration value="DefaultGeneral">
                  <xs:annotation>
                    <xs:documentation source="Gregor Hagedorn" xml:lang="en">Setting this purpose in a character grouping is a recommendation to applications with a user interface to use this as the default hierarchy for any editing or reporting purpose. The application may, however, enable the user to select any character grouping.</xs:documentation>
                  </xs:annotation>
                </xs:enumeration>
                <xs:enumeration value="DefaultDescriptionEditorView">
                  <xs:annotation>
                    <xs:documentation source="Gregor Hagedorn" xml:lang="en">Setting this purpose in a character grouping is a recommendation to applications with a user interface to use this as the default hierarchy for editing the item description data set. The application may, however, enable the user to select any character grouping.</xs:documentation>
                  </xs:annotation>
                </xs:enumeration>
                <xs:enumeration value="DefaultTerminologyEditorView">
                  <xs:annotation>
                    <xs:documentation source="Gregor Hagedorn" xml:lang="en">Setting this purpose in a character grouping is a recommendation to applications with a user interface to use this as the default hierarchy for editing the terminology. The application may, however, enable the user to select any character grouping.</xs:documentation>
                  </xs:annotation>
                </xs:enumeration>
                <xs:enumeration value="GuidedKeyBuilder">
                  <xs:annotation>
                    <xs:documentation source="Gregor Hagedorn" xml:lang="en">Setting this purpose in a character grouping is a recommendation to applications to use this as the default hierarchy for building guided keys (e. g. dichotomous keys).</xs:documentation>
                  </xs:annotation>
                </xs:enumeration>
                <xs:enumeration value="InteractiveIdentification">
                  <xs:annotation>
                    <xs:documentation source="Gregor Hagedorn" xml:lang="en">Setting this purpose in a character grouping is a recommendation to applications to use this as the default hierarchy for interactive identification.</xs:documentation>
                  </xs:annotation>
                </xs:enumeration>
                <xs:enumeration value="NaturalLanguageReporting">
                  <xs:annotation>
                    <xs:documentation source="Gregor Hagedorn" xml:lang="en">Setting this purpose in a character grouping is a recommendation to applications to use this as the default hierarchy for natural language reporting.</xs:documentation>
                  </xs:annotation>
                </xs:enumeration>
              </xs:restriction>
            </xs:simpleType>
          </xs:attribute>
        </xs:complexType>
      </xs:element>
    </xs:sequence>
  </xs:complexType>
</xs:element>

<xs:element name="Purpose" maxOccurs="unbounded">
  <xs:complexType>
    <xs:attribute name="name" use="required">
      <xs:simpleType>
        <xs:restriction base="xs:NMTOKEN">
          <xs:enumeration value="DefaultGeneral">
            <xs:annotation>
              <xs:documentation source="Gregor Hagedorn" xml:lang="en">Setting this purpose in a character grouping is a recommendation to applications with a user interface to use this as the default hierarchy for any editing or reporting purpose. The application may, however, enable the user to select any character grouping.</xs:documentation>
            </xs:annotation>
          </xs:enumeration>
          <xs:enumeration value="DefaultDescriptionEditorView">
            <xs:annotation>
              <xs:documentation source="Gregor Hagedorn" xml:lang="en">Setting this purpose in a character grouping is a recommendation to applications with a user interface to use this as the default hierarchy for editing the item description data set. The application may, however, enable the user to select any character grouping.</xs:documentation>
            </xs:annotation>
          </xs:enumeration>
          <xs:enumeration value="DefaultTerminologyEditorView">
            <xs:annotation>
              <xs:documentation source="Gregor Hagedorn" xml:lang="en">Setting this purpose in a character grouping is a recommendation to applications with a user interface to use this as the default hierarchy for editing the terminology. The application may, however, enable the user to select any character grouping.</xs:documentation>
            </xs:annotation>
          </xs:enumeration>
          <xs:enumeration value="GuidedKeyBuilder">
            <xs:annotation>
              <xs:documentation source="Gregor Hagedorn" xml:lang="en">Setting this purpose in a character grouping is a recommendation to applications to use this as the default hierarchy for building guided keys (e. g. dichotomous keys).</xs:documentation>
            </xs:annotation>
          </xs:enumeration>
          <xs:enumeration value="InteractiveIdentification">
            <xs:annotation>
              <xs:documentation source="Gregor Hagedorn" xml:lang="en">Setting this purpose in a character grouping is a recommendation to applications to use this as the default hierarchy for interactive identification.</xs:documentation>
            </xs:annotation>
          </xs:enumeration>
          <xs:enumeration value="NaturalLanguageReporting">
            <xs:annotation>
              <xs:documentation source="Gregor Hagedorn" xml:lang="en">Setting this purpose in a character grouping is a recommendation to applications to use this as the default hierarchy for natural language reporting.</xs:documentation>
            </xs:annotation>
          </xs:enumeration>
        </xs:restriction>
      </xs:simpleType>
    </xs:attribute>
  </xs:complexType>
</xs:element>

<xs:element name="CharacterGroupItem" type="CharacterGroupItemType" maxOccurs="unbounded"/>

<xs:complexType name="CharacterGroupItemType">
  <xs:annotation>
    <xs:documentation source="Gregor Hagedorn" xml:lang="en">A node in a character group</xs:documentation>
  </xs:annotation>
  <xs:sequence>
    <xs:element name="LinguisticSets" type="LinguisticSets.ComplexWordingType" minOccurs="0"/>
    <xs:element name="InternalNotes" type="string_r" minOccurs="0">
      <xs:annotation>
        <xs:documentation source="Gregor Hagedorn" xml:lang="en">Enable designer to annotate nodes in the grouping and add management comments</xs:documentation>
      </xs:annotation>
    </xs:element>
    <xs:element name="Character" minOccurs="0" maxOccurs="unbounded">
      <xs:complexType>
        <xs:sequence>
          <xs:element name="LinguisticSets" type="LinguisticSets.ComplexWordingType" minOccurs="0">
            <xs:annotation>
              <xs:documentation>Natural language wording for character node needs to be here. The relevant or possible wording is constrained by the path in the tree, so it needs to be defined in the tree, not in the flat character list. In a methodological tree the wording may have to add part hierarchy information, in a part hierarchy methodological information.</xs:documentation>
            </xs:annotation>
          </xs:element>
        </xs:sequence>
        <xs:attribute name="keyref" type="string255r" use="required"/>
      </xs:complexType>
    </xs:element>
    <xs:element name="CharacterGroupItem" type="CharacterGroupItemType" minOccurs="0" maxOccurs="unbounded"/>
  </xs:sequence>
  <xs:attribute name="key" type="string255r" use="required">
    <xs:annotation>
      <xs:documentation source="Gregor Hagedorn" xml:lang="en">The key for the character group item has been defined as required to document that an xs:key constraint exists on this attribute. It seems impossible to make existence of key optional and require keyrefs to only point to these existing keys.</xs:documentation>
    </xs:annotation>
  </xs:attribute>
</xs:complexType>

<xs:element name="LinguisticSets" type="LinguisticSets.ComplexWordingType" minOccurs="0"/>

<xs:element name="InternalNotes" type="string_r" minOccurs="0">
  <xs:annotation>
    <xs:documentation source="Gregor Hagedorn" xml:lang="en">Enable designer to annotate nodes in the grouping and add management comments</xs:documentation>
  </xs:annotation>
</xs:element>

<xs:element name="Character" minOccurs="0" maxOccurs="unbounded">
  <xs:complexType>
    <xs:sequence>
      <xs:element name="LinguisticSets" type="LinguisticSets.ComplexWordingType" minOccurs="0">
        <xs:annotation>
          <xs:documentation>Natural language wording for character node needs to be here. The relevant or possible wording is constrained by the path in the tree, so it needs to be defined in the tree, not in the flat character list. In a methodological tree the wording may have to add part hierarchy information, in a part hierarchy methodological information.</xs:documentation>
        </xs:annotation>
      </xs:element>
    </xs:sequence>
    <xs:attribute name="keyref" type="string255r" use="required"/>
  </xs:complexType>
</xs:element>

<xs:element name="LinguisticSets" type="LinguisticSets.ComplexWordingType" minOccurs="0">
  <xs:annotation>
    <xs:documentation>Natural language wording for character node needs to be here. The relevant or possible wording is constrained by the path in the tree, so it needs to be defined in the tree, not in the flat character list. In a methodological tree the wording may have to add part hierarchy information, in a part hierarchy methodological information.</xs:documentation>
  </xs:annotation>
</xs:element>

<xs:element name="CharacterGroupItem" type="CharacterGroupItemType" minOccurs="0" maxOccurs="unbounded"/>

<xs:complexType name="CharacterMeasureReferenceType">
  <xs:annotation>
    <xs:documentation source="Gregor Hagedorn" xml:lang="en">Analog to the CharacterStateReferenceType, for measures</xs:documentation>
  </xs:annotation>
  <xs:simpleContent>
    <xs:extension base="xs:double">
      <xs:attribute name="keyref" type="string255r" use="required"/>
      <xs:attribute name="Value" type="xs:double" use="required"/>
    </xs:extension>
  </xs:simpleContent>
</xs:complexType>

<xs:complexType name="CharacterReferenceType">
  <xs:annotation>
    <xs:documentation source="Gregor Hagedorn" xml:lang="en">Refers in coded item descriptions to a Character. MAY LATER NOT BE NEEDED!</xs:documentation>
  </xs:annotation>
  <xs:choice maxOccurs="unbounded">
    <xs:element name="State" type="CharacterStateReferenceType"/>
    <xs:element name="Measure" type="CharacterMeasureReferenceType"/>
  </xs:choice>
  <xs:attribute name="keyref" type="string255r" use="required"/>
</xs:complexType>

<xs:element name="State" type="CharacterStateReferenceType"/>

<xs:element name="Measure" type="CharacterMeasureReferenceType"/>

<xs:complexType name="CharacterReferenceType_NL">
  <xs:annotation>
    <xs:documentation source="Gregor Hagedorn" xml:lang="en">Like CharacterReferenceType, but for usage in the NaturalLanguageDescription markup container (including Wording elements)</xs:documentation>
    <xs:appinfo source="internal note">CharacterReferenceType_NL is similar to CharacterReferenceType, but not derived by extension, since not only the Wording element has to be added, but also state element changed to a different type allowing Wording inside.</xs:appinfo>
  </xs:annotation>
  <xs:choice maxOccurs="unbounded">
    <xs:element name="State" type="CharacterStateReferenceType_NL" minOccurs="0" maxOccurs="unbounded"/>
    <xs:element name="Measure" type="CharacterMeasureReferenceType" minOccurs="0" maxOccurs="unbounded"/>
    <xs:element name="Wording" type="MarkupWordingType" minOccurs="0"/>
  </xs:choice>
  <xs:attribute name="keyref" type="string255r" use="required"/>
</xs:complexType>

<xs:element name="State" type="CharacterStateReferenceType_NL" minOccurs="0" maxOccurs="unbounded"/>

<xs:element name="Measure" type="CharacterMeasureReferenceType" minOccurs="0" maxOccurs="unbounded"/>

<xs:element name="Wording" type="MarkupWordingType" minOccurs="0"/>

<xs:complexType name="CharacterStateDefinitionType">
  <xs:annotation>
    <xs:documentation source="Gregor Hagedorn" xml:lang="en">Used in global and local character state definitions</xs:documentation>
  </xs:annotation>
  <xs:sequence>
    <xs:element name="LinguisticSets" type="LinguisticSets.BasicWordingType"/>
    <xs:element name="InternalNotes" type="string_r" minOccurs="0">
      <xs:annotation>
        <xs:documentation source="Gregor Hagedorn" xml:lang="en">Internal notes of the designer, 
not multilingual.</xs:documentation>
      </xs:annotation>
    </xs:element>
    <xs:element name="Resources" type="ResourceReferencesType" minOccurs="0">
      <xs:annotation>
        <xs:documentation source="Gregor Hagedorn" xml:lang="en">Resources linked to a state definition, e. g. images illustrating expression of the state.</xs:documentation>
      </xs:annotation>
    </xs:element>
  </xs:sequence>
  <xs:attribute name="type" use="optional">
    <xs:annotation>
      <xs:documentation source="Gregor Hagedorn" xml:lang="en">This attribute is currently not used, instead the key of the StateSet has been fixed for special states to SpecialStates. Needs discussion!</xs:documentation>
    </xs:annotation>
    <xs:simpleType>
      <xs:restriction base="xs:NMTOKEN">
        <xs:enumeration value="SpecialState"/>
        <xs:enumeration value="GlobalState"/>
        <xs:enumeration value="LocalState"/>
      </xs:restriction>
    </xs:simpleType>
  </xs:attribute>
  <xs:attribute name="key" type="string255r" use="required"/>
</xs:complexType>

<xs:element name="LinguisticSets" type="LinguisticSets.BasicWordingType"/>

<xs:element name="InternalNotes" type="string_r" minOccurs="0">
  <xs:annotation>
    <xs:documentation source="Gregor Hagedorn" xml:lang="en">Internal notes of the designer, 
not multilingual.</xs:documentation>
  </xs:annotation>
</xs:element>

<xs:element name="Resources" type="ResourceReferencesType" minOccurs="0">
  <xs:annotation>
    <xs:documentation source="Gregor Hagedorn" xml:lang="en">Resources linked to a state definition, e. g. images illustrating expression of the state.</xs:documentation>
  </xs:annotation>
</xs:element>