<attributeGroup name="eventStateAmericanFootball">
    <attribute name="period-value" type="string" use="optional">
        <annotation>
            <documentation>An interger. 1,2,3,4 for the main quarters. 5,6,7,etc. for overtime periods (our shootout periods, for Canadian Football).</documentation>
        </annotation>
    </attribute>
    <attribute name="period-time-elapsed" type="string" use="optional">
        <annotation>
            <documentation>The time elapsed since the beginning of the period.</documentation>
        </annotation>
    </attribute>
    <attribute name="period-time-remaining" type="string" use="optional">
        <annotation>
            <documentation>The time remaining in the period.</documentation>
        </annotation>
    </attribute>
    <attribute name="clock-state" use="optional">
        <annotation>
            <documentation>Whether the clock is running or stopped.</documentation>
        </annotation>
        <simpleType>
            <restriction base="string">
                <enumeration value="stopped" />
                <enumeration value="running" />
            </restriction>
        </simpleType>
    </attribute>
    <attribute name="team-in-possession-idref" type="IDREF" use="optional">
        <annotation>
            <documentation>The ID of the team with the football.</documentation>
        </annotation>
    </attribute>
    <attribute name="down" use="optional">
        <annotation>
            <documentation>The current down.  Valid values are 1,2,3,4,5, with 5th down used for Canadian Football.</documentation>
        </annotation>
        <simpleType>
            <restriction base="string">
                <enumeration value="1" />
                <enumeration value="2" />
                <enumeration value="3" />
                <enumeration value="4" />
                <enumeration value="5" />
            </restriction>
        </simpleType>
    </attribute>
    <attribute name="distance-for-1st-down" type="string" use="optional">
        <annotation>
            <documentation>The distance between the current line of scrimmage and the first down marker. In yards. The word goal is used for, say, 3rd-and-goal situations. The word kick is used for an extra-point attempt.</documentation>
        </annotation>
    </attribute>
    <attribute name="field-side" use="optional">
        <annotation>
            <documentation>Which side of the field the event is taking place.  Either "home" or "visiting".</documentation>
        </annotation>
        <simpleType>
            <restriction base="string">
                <enumeration value="home" />
                <enumeration value="away" />
            </restriction>
        </simpleType>
    </attribute>
    <attribute name="field-line" type="string" use="optional">
        <annotation>
            <documentation>The line of scrimmage. Where the ball is at the start of play or play-segment.</documentation>
        </annotation>
    </attribute>
    <attribute name="sequence-number" type="string" use="optional">
        <annotation>
            <documentation>Usually an integer</documentation>
        </annotation>
    </attribute>
</attributeGroup>