<xs:attributeGroup name="eventStateAmericanFootball">
    <xs:attribute name="clock-state" use="optional">
        <xs:annotation>
            <xs:documentation>Whether the clock is running or stopped.</xs:documentation>
        </xs:annotation>
        <xs:simpleType>
            <xs:restriction base="xs:string">
                <xs:enumeration value="stopped" />
                <xs:enumeration value="running" />
            </xs:restriction>
        </xs:simpleType>
    </xs:attribute>
    <xs:attribute name="team-in-possession-idref" type="xs:IDREF" use="optional">
        <xs:annotation>
            <xs:documentation>The ID of the team with the football.</xs:documentation>
        </xs:annotation>
    </xs:attribute>
    <xs:attribute name="down" use="optional">
        <xs:annotation>
            <xs:documentation>The current down. Valid values are 1,2,3,4,5.</xs:documentation>
        </xs:annotation>
        <xs:simpleType>
            <xs:restriction base="xs:string">
                <xs:enumeration value="1" />
                <xs:enumeration value="2" />
                <xs:enumeration value="3" />
                <xs:enumeration value="4" />
                <xs:enumeration value="5" />
            </xs:restriction>
        </xs:simpleType>
    </xs:attribute>
    <xs:attribute name="distance-for-1st-down" type="xs:string" use="optional">
        <xs:annotation>
            <xs:documentation>The distance between the current line of scrimmage and the line to gain, 10 yards downfield from the start of possession. In yards. The word goal is used when the distance to the goal line is less than 10 yards. The word kick is used for kick-scoring attempt.</xs:documentation>
        </xs:annotation>
    </xs:attribute>
    <xs:attribute name="field-side" use="optional">
        <xs:annotation>
            <xs:documentation>Which side of the field the event is taking place.  Either "home" or "away".</xs:documentation>
        </xs:annotation>
        <xs:simpleType>
            <xs:restriction base="xs:string">
                <xs:enumeration value="home" />
                <xs:enumeration value="away" />
            </xs:restriction>
        </xs:simpleType>
    </xs:attribute>
    <xs:attribute name="field-line" type="xs:string" use="optional">
        <xs:annotation>
            <xs:documentation>The line of scrimmage. The yard line where the ball is placed at the start of play.</xs:documentation>
        </xs:annotation>
    </xs:attribute>
</xs:attributeGroup>