<xsd:element name="oval_definitions">
    <xsd:annotation>
        <xsd:documentation>The oval_definitions element is the root of an OVAL Definition Document. Its purpose is to bind together the major sections of a document - generator, definitions, tests, objects, states, and variables - which are the children of the root element.</xsd:documentation>
        <xsd:appinfo>
            <sch:pattern id="empty_def_doc" xmlns:sch="http://purl.oclc.org/dsdl/schematron">
                <sch:rule context="oval-def:oval_definitions">
                    <sch:assert test="oval-def:definitions or oval-def:tests or oval-def:objects or oval-def:states or oval-def:variables">A valid OVAL Definition document must contain at least one definitions, tests, objects, states, or variables element. The optional definitions, tests, objects, states, and variables sections define the specific characteristics that should be evaluated on a system to determine the truth values of the OVAL Definition Document. To be valid though, at least one definitions, tests, objects, states, or variables element must be present.</sch:assert>
                </sch:rule>
            </sch:pattern>
        </xsd:appinfo>
    </xsd:annotation>
    <xsd:complexType>
        <xsd:sequence>
            <xsd:element name="generator" type="oval:GeneratorType" minOccurs="1" maxOccurs="1">
                <xsd:annotation>
                    <xsd:documentation>The required generator section provides information about when the definition file was compiled and under what version.</xsd:documentation>
                </xsd:annotation>
            </xsd:element>
            <xsd:element name="definitions" type="oval-def:DefinitionsType" minOccurs="0" maxOccurs="1">
                <xsd:annotation>
                    <xsd:documentation>The optional definitions section contains 1 or more definitions.</xsd:documentation>
                </xsd:annotation>
            </xsd:element>
            <xsd:element name="tests" type="oval-def:TestsType" minOccurs="0" maxOccurs="1">
                <xsd:annotation>
                    <xsd:documentation>The optional tests section contains 1 or more tests.</xsd:documentation>
                </xsd:annotation>
            </xsd:element>
            <xsd:element name="objects" type="oval-def:ObjectsType" minOccurs="0" maxOccurs="1">
                <xsd:annotation>
                    <xsd:documentation>The optional objects section contains 1 or more objects.</xsd:documentation>
                </xsd:annotation>
            </xsd:element>
            <xsd:element name="states" type="oval-def:StatesType" minOccurs="0" maxOccurs="1">
                <xsd:annotation>
                    <xsd:documentation>The optional states section contains 1 or more states.</xsd:documentation>
                </xsd:annotation>
            </xsd:element>
            <xsd:element name="variables" type="oval-def:VariablesType" minOccurs="0" maxOccurs="1">
                <xsd:annotation>
                    <xsd:documentation>The optional variables section contains 1 or more variables.</xsd:documentation>
                </xsd:annotation>
            </xsd:element>
            <xsd:element ref="ds:Signature" minOccurs="0" maxOccurs="1">
                <xsd:annotation>
                    <xsd:documentation>The optional Signature element allows an XML Signature as defined by the W3C to be attached to the document. This allows authentication and data integrity to be provided to the user. Enveloped signatures are supported. More information about the official W3C Recommendation regarding XML digital signatures can be found at http://www.w3.org/TR/xmldsig-core/.</xsd:documentation>
                </xsd:annotation>
            </xsd:element>
        </xsd:sequence>
    </xsd:complexType>
    <xsd:key name="definitionKey">
        <xsd:annotation>
            <xsd:documentation>Enforce uniqueness amongst the ids differentiating the individual definition elements.</xsd:documentation>
        </xsd:annotation>
        <xsd:selector xpath="oval-def:definitions/oval-def:definition" />
        <xsd:field xpath="@id" />
    </xsd:key>
    <xsd:key name="testKey">
        <xsd:annotation>
            <xsd:documentation>Enforce uniqueness amongst the ids differentiating the individual test elements.</xsd:documentation>
        </xsd:annotation>
        <xsd:selector xpath="oval-def:tests/*" />
        <xsd:field xpath="@id" />
    </xsd:key>
    <xsd:key name="objectKey">
        <xsd:annotation>
            <xsd:documentation>Enforce uniqueness amongst the ids differentiating the individual object elements.</xsd:documentation>
        </xsd:annotation>
        <xsd:selector xpath="oval-def:objects/*" />
        <xsd:field xpath="@id" />
    </xsd:key>
    <xsd:key name="stateKey">
        <xsd:annotation>
            <xsd:documentation>Enforce uniqueness amongst the ids differentiating the individual state elements.</xsd:documentation>
        </xsd:annotation>
        <xsd:selector xpath="oval-def:states/*" />
        <xsd:field xpath="@id" />
    </xsd:key>
    <xsd:key name="variableKey">
        <xsd:annotation>
            <xsd:documentation>Enforce uniqueness amongst the ids differentiating the individual variable elements.</xsd:documentation>
        </xsd:annotation>
        <xsd:selector xpath="oval-def:variables/*" />
        <xsd:field xpath="@id" />
    </xsd:key>
    <xsd:keyref name="extendKeyRef" refer="oval-def:definitionKey">
        <xsd:annotation>
            <xsd:documentation>Requires each definition reference to refer to a valid definition id.</xsd:documentation>
        </xsd:annotation>
        <xsd:selector xpath=".//*" />
        <xsd:field xpath="@definition_ref" />
    </xsd:keyref>
    <xsd:keyref name="testKeyRef" refer="oval-def:testKey">
        <xsd:annotation>
            <xsd:documentation>Requires each test reference to refer to a valid test id.</xsd:documentation>
        </xsd:annotation>
        <xsd:selector xpath=".//*" />
        <xsd:field xpath="@test_ref" />
    </xsd:keyref>
    <xsd:keyref name="objectKeyRef" refer="oval-def:objectKey">
        <xsd:annotation>
            <xsd:documentation>Requires each object reference to refer to a valid object id.</xsd:documentation>
        </xsd:annotation>
        <xsd:selector xpath=".//*" />
        <xsd:field xpath="@object_ref" />
    </xsd:keyref>
    <xsd:keyref name="stateKeyRef" refer="oval-def:stateKey">
        <xsd:annotation>
            <xsd:documentation>Requires each state reference to refer to a valid state id.</xsd:documentation>
        </xsd:annotation>
        <xsd:selector xpath=".//*" />
        <xsd:field xpath="@state_ref" />
    </xsd:keyref>
    <xsd:keyref name="variableKeyRef" refer="oval-def:variableKey">
        <xsd:annotation>
            <xsd:documentation>Requires each variable reference to refer to a valid variable id.</xsd:documentation>
        </xsd:annotation>
        <xsd:selector xpath=".//*" />
        <xsd:field xpath="@var_ref" />
    </xsd:keyref>
    <xsd:keyref name="object_referenceKeyRef" refer="oval-def:objectKey">
        <xsd:annotation>
            <xsd:documentation>Require each object reference in a set element to refer to a valid object id.</xsd:documentation>
        </xsd:annotation>
        <xsd:selector xpath=".//oval-def:object_reference" />
        <xsd:field xpath="." />
    </xsd:keyref>
    <xsd:keyref name="filterKeyRef" refer="oval-def:stateKey">
        <xsd:annotation>
            <xsd:documentation>Require each filter in a set element to refer to a valid state id.</xsd:documentation>
        </xsd:annotation>
        <xsd:selector xpath=".//oval-def:filter" />
        <xsd:field xpath="." />
    </xsd:keyref>
</xsd:element>