The optional timeUnit attribute defines the unit name for the SummaryStatisticsTimeType.
Source
<xs:complexType name="SummaryStatisticsTimeType"><xs:annotation><xs:documentation>The SummaryStatisticsTimeType defines a summary of a single time statistical value.</xs:documentation></xs:annotation><xs:complexContent><xs:extension base="SummaryStatisticsType"><xs:attribute name="timeUnit" type="xs:token"><xs:annotation><xs:documentation>The optional timeUnit attribute defines the unit name for the SummaryStatisticsTimeType.</xs:documentation></xs:annotation></xs:attribute></xs:extension></xs:complexContent></xs:complexType>
<xs:attribute name="timeUnit" type="xs:token"><xs:annotation><xs:documentation>The optional timeUnit attribute defines the unit name for the SummaryStatisticsTimeType.</xs:documentation></xs:annotation></xs:attribute>