<?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="3.1.1">
        <annotation>
                <appinfo source="urn:opengis:specification:gml:schema-xsd:observation:3.1.1">observation.xsd</appinfo>
                <documentation>Observation schema for GML 3.1     
    Copyright (c) 2002-2005 OGC, All Rights Reserved.
        For conditions, see OGC Software Notice http://www.opengeospatial.org/about/?page=ipr</documentation>
        </annotation>
        <!-- =================================================================== -->
        <!-- ===       includes and imports ============================================ -->
        <include schemaLocation="feature.xsd"/>
        <include schemaLocation="direction.xsd"/>
        <include schemaLocation="valueObjects.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>
                <sequence minOccurs="0">
                        <choice>
                                <element ref="gml:_Feature"/>
                                <element ref="gml:_Geometry"/>
                        </choice>
                </sequence>
                <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:validTime"/>
                                        <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:Observation"/>
        <!-- =========================================================== -->
        <complexType name="DirectedObservationType">
                <complexContent>
                        <extension base="gml:ObservationType">
                                <sequence>
                                        <element ref="gml:direction"/>
                                </sequence>
                        </extension>
                </complexContent>
        </complexType>
        <!-- =========================================================== -->
        <element name="DirectedObservationAtDistance" type="gml:DirectedObservationAtDistanceType" substitutionGroup="gml:DirectedObservation"/>
        <!-- =========================================================== -->
        <complexType name="DirectedObservationAtDistanceType">
                <complexContent>
                        <extension base="gml:DirectedObservationType">
                                <sequence>
                                        <element name="distance" type="gml:MeasureType"/>
                                </sequence>
                        </extension>
                </complexContent>
        </complexType>
        <!-- =========================================================== -->
</schema>