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  ~ or more contributor license agreements. See the NOTICE file
  ~ distributed with this work for additional information
  ~ regarding copyright ownership. The ASF licenses this file
  ~ to you under the Apache License, Version 2.0 (the
  ~ "License"); you may not use this file except in compliance
  ~ with the License. You may obtain a copy of the License at
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  ~ http://www.apache.org/licenses/LICENSE-2.0
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  ~ "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  ~ KIND, either express or implied. See the License for the
  ~ specific language governing permissions and limitations
  ~ under the License.
  -->

<!-- mails.xsd -->

<xsd:schema xmlns:xsd="http://www.example.org/2001/XMLSchema">

 <xsd:element name="mails" type="mailsType" />

 <xsd:complexType name="mailsType">
  <xsd:sequence minOccurs="0" maxOccurs="unbounded">
   <xsd:element name="mail" type="mailType" />
  </xsd:sequence>
 </xsd:complexType>

 <xsd:complexType name="mailType">
  <xsd:sequence>
   <xsd:element name="envelope" type="envelopeType" />
   <xsd:element name="body" type="bodyType" />
   <xsd:element name="attachment" type="attachmentType"
		minOccurs="0" maxOccurs="unbounded" />
  </xsd:sequence>
  <xsd:attribute use="required" name="id" type="xsd:integer" />
 </xsd:complexType>

 <xsd:element name="header">
  <xsd:complexType>
   <xsd:simpleContent>
    <xsd:extension base="xsd:string">
     <xsd:attribute ref="name" use="required" />
    </xsd:extension>
   </xsd:simpleContent>
  </xsd:complexType>
 </xsd:element>

 <xsd:element name="Date" type="xsd:dateTime" />

 <xsd:complexType name="envelopeType">
  <xsd:sequence>
   <xsd:element name="From" type="xsd:string" />
   <xsd:element name="To" type="xsd:string" />
   <xsd:element ref="Date" />
   <xsd:element name="Subject" type="xsd:string" />
   <xsd:element ref="header" minOccurs="0" maxOccurs="unbounded" />
  </xsd:sequence>
  <xsd:attribute name="From" type="xsd:string" use="required" />
 </xsd:complexType>

 <xsd:simpleType name="bodyType">
  <xsd:restriction base="xsd:string" />
 </xsd:simpleType>

 <xsd:complexType name="attachmentType">
  <xsd:group ref="attachmentContent" />
  <xsd:attribute ref="name" use="required" />
 </xsd:complexType>

 <xsd:group name="attachmentContent">
  <xsd:sequence>
   <xsd:element name="mimetype">
    <xsd:complexType>
     <xsd:attributeGroup ref="mimeTypeAttributes" />
    </xsd:complexType>
   </xsd:element>
   <xsd:element name="content" type="xsd:string" minOccurs="0" />
  </xsd:sequence>
 </xsd:group>

 <xsd:attribute name="name" type="xsd:string" />

 <xsd:attributeGroup name="mimeTypeAttributes">
  <xsd:attribute name="type" type="mimeTopLevelType" use="required" />
  <xsd:attribute name="subtype" type="xsd:string" use="required" />
 </xsd:attributeGroup>

 <xsd:simpleType name="mimeTopLevelType">
  <xsd:restriction base="xsd:string">
   <xsd:enumeration value="text" />
   <xsd:enumeration value="multipart" />
   <xsd:enumeration value="application" />
   <xsd:enumeration value="message" />
   <xsd:enumeration value="image" />
   <xsd:enumeration value="audio" />
   <xsd:enumeration value="video" />
  </xsd:restriction>
 </xsd:simpleType>

</xsd:schema>