<xs:attributeGroup name="recurrenceRuleAttributes">
    <xs:annotation>
        <xs:documentation>A group of attributes aligning with iCalendar RECUR - see http://www.ietf.org/rfc/rfc2445.txt</xs:documentation>
    </xs:annotation>
    <xs:attribute name="freq" use="required">
        <xs:annotation>
            <xs:documentation>The FREQ rule part identifies the type of recurrence rule.</xs:documentation>
        </xs:annotation>
        <xs:simpleType>
            <xs:restriction base="xs:string">
                <xs:enumeration value="SECONDLY" />
                <xs:enumeration value="MINUTELY" />
                <xs:enumeration value="HOURLY" />
                <xs:enumeration value="DAILY" />
                <xs:enumeration value="WEEKLY" />
                <xs:enumeration value="MONTHLY" />
                <xs:enumeration value="YEARLY" />
            </xs:restriction>
        </xs:simpleType>
    </xs:attribute>
    <xs:attribute name="interval" type="xs:positiveInteger">
        <xs:annotation>
            <xs:documentation>The INTERVAL rule part contains a positive integer representing how often the recurrence rule repeats.</xs:documentation>
        </xs:annotation>
    </xs:attribute>
    <xs:attribute name="until" type="DateOptTimeType">
        <xs:annotation>
            <xs:documentation>The UNTIL rule part defines a date-time value which bounds the recurrence rule in an inclusive manner.</xs:documentation>
        </xs:annotation>
    </xs:attribute>
    <xs:attribute name="count" type="xs:positiveInteger">
        <xs:annotation>
            <xs:documentation>The COUNT rule part defines the number of occurrences at which to range-bound the recurrence.</xs:documentation>
        </xs:annotation>
    </xs:attribute>
    <xs:attribute name="bysecond">
        <xs:annotation>
            <xs:documentation>The BYSECOND rule part specifies a space separated list of seconds within a minute</xs:documentation>
        </xs:annotation>
        <xs:simpleType>
            <xs:restriction base="BySecondListType">
                <xs:minLength value="1" />
            </xs:restriction>
        </xs:simpleType>
    </xs:attribute>
    <xs:attribute name="byminute">
        <xs:annotation>
            <xs:documentation>The BYMINUTE rule part specifies a space separated list of minutes within an hour.</xs:documentation>
        </xs:annotation>
        <xs:simpleType>
            <xs:restriction base="ByMinuteListType">
                <xs:minLength value="1" />
            </xs:restriction>
        </xs:simpleType>
    </xs:attribute>
    <xs:attribute name="byhour">
        <xs:annotation>
            <xs:documentation>The BYHOUR rule part specifies space separated list of hours of the day.</xs:documentation>
        </xs:annotation>
        <xs:simpleType>
            <xs:restriction base="ByHourListType">
                <xs:minLength value="1" />
            </xs:restriction>
        </xs:simpleType>
    </xs:attribute>
    <xs:attribute name="byday">
        <xs:annotation>
            <xs:documentation>The BYDAY rule part specifies a space separated list of days of the week</xs:documentation>
        </xs:annotation>
        <xs:simpleType>
            <xs:restriction base="ByDayListType">
                <xs:minLength value="1" />
            </xs:restriction>
        </xs:simpleType>
    </xs:attribute>
    <xs:attribute name="bymonthday">
        <xs:annotation>
            <xs:documentation>The BYMONTHDAY rule part specifies a space separated list of days of the month.</xs:documentation>
        </xs:annotation>
        <xs:simpleType>
            <xs:restriction base="ByMonthDayListType">
                <xs:minLength value="1" />
            </xs:restriction>
        </xs:simpleType>
    </xs:attribute>
    <xs:attribute name="bymonth">
        <xs:annotation>
            <xs:documentation>The BYMONTH rule part specifies a space separated list of months of the year.</xs:documentation>
        </xs:annotation>
        <xs:simpleType>
            <xs:restriction base="ByMonthListType">
                <xs:minLength value="1" />
            </xs:restriction>
        </xs:simpleType>
    </xs:attribute>
    <xs:attribute name="byyearday">
        <xs:annotation>
            <xs:documentation>The BYYEARDAY rule part specifies a  space separated list of days of the year.</xs:documentation>
        </xs:annotation>
        <xs:simpleType>
            <xs:restriction base="ByYearDayListType">
                <xs:minLength value="1" />
            </xs:restriction>
        </xs:simpleType>
    </xs:attribute>
    <xs:attribute name="byweekno">
        <xs:annotation>
            <xs:documentation>The BYWEEKNO rule part specifies a space separated list of ordinals specifying weeks of the year.</xs:documentation>
        </xs:annotation>
        <xs:simpleType>
            <xs:restriction base="ByWeekNoListType">
                <xs:minLength value="1" />
            </xs:restriction>
        </xs:simpleType>
    </xs:attribute>
    <xs:attribute name="bysetpos">
        <xs:annotation>
            <xs:documentation>The BYSETPOS rule part specifies a space separated list of values which corresponds to the nth occurrence
   within the set of events specified by the rule.</xs:documentation>
        </xs:annotation>
        <xs:simpleType>
            <xs:restriction base="BySetposListType">
                <xs:minLength value="1" />
            </xs:restriction>
        </xs:simpleType>
    </xs:attribute>
    <xs:attribute name="wkst">
        <xs:annotation>
            <xs:documentation>The WKST rule part specifies the day on which the workweek starts.</xs:documentation>
        </xs:annotation>
        <xs:simpleType>
            <xs:restriction base="xs:string">
                <xs:enumeration value="MO" />
                <xs:enumeration value="TU" />
                <xs:enumeration value="WE" />
                <xs:enumeration value="TH" />
                <xs:enumeration value="FR" />
                <xs:enumeration value="SA" />
                <xs:enumeration value="SU" />
            </xs:restriction>
        </xs:simpleType>
    </xs:attribute>
</xs:attributeGroup>