<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
    
    <xs:include schemaLocation="value.xsd"/>
    <xs:include schemaLocation="angle.xsd"/>
    <xs:include schemaLocation="measure.xsd"/>
    <xs:include schemaLocation="geometry.xsd"/>
    <xs:include schemaLocation="util.xsd"/>
    
    <xs:annotation>
        <xs:documentation xml:lang="en">
            Jeospace orbit types and elements
        </xs:documentation>
    </xs:annotation>
    
    <xs:simpleType name="epochFormatType">
        <xs:restriction base="xs:NMTOKEN">
            <xs:enumeration value="jd"/>
            <xs:enumeration value="mjd"/>
            <xs:enumeration value="tle"/>
            <xs:enumeration value="cd"/>
            <xs:enumeration value="packed"/>
        </xs:restriction>
    </xs:simpleType>
    
    <xs:complexType name="epochType">
        <xs:attribute name="value" type="xs:token" use="required"/>
        <xs:attribute name="fmt" type="epochFormatType" use="required"/>
    </xs:complexType>
    
    <xs:element name="epoch" type="epochType"/>
    
    <xs:element name="incl" type="angleType"/>
    <xs:element name="ascn" type="angleType"/>
    <xs:element name="argp" type="angleType"/>
    <xs:element name="anml" type="angleType"/>
    <xs:element name="mnmo" type="angleType"/>
    
    <xs:element name="dstp" type="nonNegativeLengthType"/>
    
    <xs:element name="OrbitalElements">
        <xs:complexType>
            <xs:sequence>
                <xs:element name="ecc" type="nonNegativeDoubleValueType"/>
                <xs:element ref="incl"/>
                <xs:element ref="ascn"/>
                <xs:element ref="argp"/>
                <xs:choice>
                    <xs:sequence>
                        <xs:annotation>
                            <xs:documentation xml:lang="en">
                                This choice cooresponds to the 'planet' format which describes a low 
                                ellipticity orbit.
                            </xs:documentation>
                        </xs:annotation>
                        <xs:element ref="smax"/>
                        <xs:element ref="anml"/>
                    </xs:sequence>
                    <xs:sequence>
                        <xs:annotation>
                            <xs:documentation xml:lang="en">
                                This choice cooresponds to the 'satellite' format. (Actually should be 
                                'earth satellite' format.) The elements are derived -primarily- from
                                Two Line Element sets published by NASA (among others) describing the
                                Earth orbiting satellites.
                            </xs:documentation>
                        </xs:annotation>
                        <xs:element ref="anml"/>
                        <xs:element ref="mnmo"/>
                        <xs:element name="drgc" type="nonNegativeDoubleValueType"/> 
                    </xs:sequence>
                    <xs:sequence>
                        <xs:annotation>
                            <xs:documentation xml:lang="en">
                                This choice cooresponds to the 'comet' format which describes a high 
                                ellipticity orbit where the elements are derived from sightings near 
                                the point of perigee.
                            </xs:documentation>
                        </xs:annotation>
                        <xs:element ref="dstp"/>
                        <xs:element name="timp" type="epochType"/>
                    </xs:sequence>
                </xs:choice>
                <xs:element ref="epoch"/>
            </xs:sequence>
        </xs:complexType>
    </xs:element>
    
    <xs:element name="Root">
        <xs:complexType>
            <xs:attribute ref="id" use="required"/>
        </xs:complexType>
    </xs:element>
    
    <xs:element name="World">
        <xs:complexType>
            <xs:sequence>
                <xs:element ref="Identification"/>
                <xs:element ref="ReferenceFrame"/>
                <xs:choice>
                    <xs:element ref="class"/>
                    <xs:sequence>
                        <xs:element ref="Ellipsoid"/>
                        <xs:element ref="Mass"/>
                        <xs:element ref="OrbitalElements"/>
                    </xs:sequence>
                </xs:choice>
            </xs:sequence>
        </xs:complexType>
    </xs:element>
    
    <xs:element name="Satellite">
        <xs:complexType>
            <xs:sequence>
                <xs:element ref="Identification"/>
                <xs:element ref="ReferenceFrame"/>
                <xs:element ref="OrbitalElements"/>
            </xs:sequence>
        </xs:complexType>
    </xs:element>
    
</xs:schema>