<?xml version="1.0" encoding="UTF-8" ?>
<schema targetNamespace="http://www.opengis.net/gml" xmlns="http://www.w3.org/2001/XMLSchema" xmlns:gml="http://www.opengis.net/gml" elementFormDefault="qualified" version="3.0.1">
	<annotation>
		<appinfo source="urn:opengis:specification:gml:schema-xsd:observation:v3.0.1">observation.xsd</appinfo>
		<documentation>Observation schema for GML 3.0     
    </documentation>
	</annotation> <!-- =================================================================== --> <!-- ===       includes and imports ============================================ -->
	<include schemaLocation="feature.xsd" />
	<include schemaLocation="direction.xsd" /> <!-- =================================================================== --> <!-- =================== properties =================================== -->
	<element name="using" type="gml:FeaturePropertyType">
		<annotation>
			<documentation>This element contains or points to a description of a sensor, instrument or procedure used for the observation</documentation>
		</annotation>
	</element> <!-- =================================================================== -->
	<element name="target" type="gml:TargetPropertyType">
		<annotation>
			<documentation>This element contains or points to the specimen, region or station which is the object of the observation</documentation>
		</annotation>
	</element> <!-- =================================================================== -->
	<element name="subject" type="gml:TargetPropertyType" substitutionGroup="gml:target">
		<annotation>
			<documentation>Synonym for target - common word used for photographs</documentation>
		</annotation>
	</element> <!-- =================================================================== -->
	<complexType name="TargetPropertyType">
		<annotation>
			<documentation>Container for an object representing the target or subject of an observation.</documentation>
		</annotation>
		<choice minOccurs="0">
			<element ref="gml:_Feature" />
			<element ref="gml:_Geometry" />
		</choice>
		<attributeGroup ref="gml:AssociationAttributeGroup" />
	</complexType> <!-- =================================================================== -->
	<element name="resultOf" type="gml:AssociationType">
		<annotation>
			<documentation>The result of the observation: an image, external object, etc</documentation>
		</annotation>
	</element> <!-- =================================================================== --> <!-- ===================== Features =========================== -->
	<element name="Observation" type="gml:ObservationType" substitutionGroup="gml:_Feature" /> <!-- =========================================================== -->
	<complexType name="ObservationType">
		<complexContent>
			<extension base="gml:AbstractFeatureType">
				<sequence>
					<element ref="gml:timeStamp" />
					<element ref="gml:using" minOccurs="0" />
					<element ref="gml:target" minOccurs="0" />
					<element ref="gml:resultOf" />
				</sequence>
			</extension>
		</complexContent>
	</complexType> <!-- =========================================================== -->
	<element name="DirectedObservation" type="gml:DirectedObservationType" substitutionGroup="gml:_Feature" /> <!-- =========================================================== -->
	<complexType name="DirectedObservationType">
		<complexContent>
			<extension base="gml:ObservationType">
				<sequence>
					<element ref="gml:direction" />
				</sequence>
			</extension>
		</complexContent>
	</complexType> <!-- =========================================================== -->
</schema>