XSD Specification
<xs:simpleType name="IfcActionSourceTypeEnum">
<xs:restriction base="xs:string">
<xs:enumeration value="dead_load_g"/>
<xs:enumeration value="completion_g1"/>
<xs:enumeration value="live_load_q"/>
<xs:enumeration value="snow_s"/>
<xs:enumeration value="wind_w"/>
<xs:enumeration value="prestressing_p"/>
<xs:enumeration value="settlement_u"/>
<xs:enumeration value="temperature_t"/>
<xs:enumeration value="earthquake_e"/>
<xs:enumeration value="fire"/>
<xs:enumeration value="impulse"/>
<xs:enumeration value="impact"/>
<xs:enumeration value="transport"/>
<xs:enumeration value="erection"/>
<xs:enumeration value="propping"/>
<xs:enumeration value="system_imperfection"/>
<xs:enumeration value="shrinkage"/>
<xs:enumeration value="creep"/>
<xs:enumeration value="lack_of_fit"/>
<xs:enumeration value="buoyancy"/>
<xs:enumeration value="ice"/>
<xs:enumeration value="current"/>
<xs:enumeration value="wave"/>
<xs:enumeration value="rain"/>
<xs:enumeration value="brakes"/>
<xs:enumeration value="userdefined"/>
<xs:enumeration value="notdefined"/>
</xs:restriction>
</xs:simpleType>