<simpleType name="TimeUnitType">
    <annotation>
        <appinfo source="urn:opengis:specification:gml:schema-xsd:temporal:3.1.1">temporal.xsd</appinfo>
        <documentation xml:lang="en">
        Standard units for measuring time intervals (see ISO 31-1).
      </documentation>
    </annotation>
    <union>
        <simpleType>
            <restriction base="string">
                <enumeration value="year" />
                <enumeration value="day" />
                <enumeration value="hour" />
                <enumeration value="minute" />
                <enumeration value="second" />
            </restriction>
        </simpleType>
        <simpleType>
            <restriction base="string">
                <pattern value="other:\w{2,}" />
            </restriction>
        </simpleType>
    </union>
</simpleType>

• TimeUnitType
• gml:unit