<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified">
  <xs:annotation>
    <xs:documentation> The JSBSim v2.0 configuration file format (JSBSim-ML) is the medium for describing 
      aircraft flight characteristics to the JSBSim code. For more information about JSBSim, see the
      web site at: <a href="http://www.jsbsim.org">www.jsbsim.org</a>.
      <p/>
      The config file format stores and conveys the characteristics of any unique aircraft to the JSBSim
      executable. The information that is specified in the configuration file includes:
      <ul>
        <li>Administrative</li>
        <li>Geometric and measurement</li>
        <li>Mass and weight/balance</li>
        <li>Buoyant forces</li>
        <li>Ground reactions</li>
        <li>External reactions</li>
        <li>Propulsion</li>
        <li>Systems, Autopilot, and Flight Control</li>
        <li>Aerodynamics</li>
        <li>Input/Output</li>
      </ul>
      <p/>
      The basic structure of the configuration file at the highest level is shown beginning with the
      fdm_config element definition.
    </xs:documentation>
  </xs:annotation>
  <xs:element name="fdm_config">
    <xs:annotation>
      <xs:documentation> This is the root element for a JSBSim config file. </xs:documentation>
    </xs:annotation>
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="fileheader" />
        <!--The file creation information. -->
        <xs:element ref="metrics" />
        <!--The geometric information for the aircraft model. -->
        <xs:element ref="mass_balance" />
        <!-- The weight and balance information for the aircraft model.</xs:annotation -->
        <xs:element ref="ground_reactions" minOccurs="0" />
        <!--The landing gear and/or structural contact point information for the aircraft model. -->
        <xs:element ref="external_reactions" minOccurs="0" />
        <!--The external reactions information for the aircraft model. -->
        <xs:element ref="buoyant_forces" minOccurs="0" />
        <!--The external reactions information for the aircraft model. -->
        <xs:element ref="propulsion" minOccurs="0" />
        <!-- The propulsion system information for the aircraft model. -->
        <xs:element ref="system" minOccurs="0" maxOccurs="unbounded"/>
        <!-- The systems reference -->
        <xs:element ref="autopilot" minOccurs="0" />
        <!-- The autopilot definition for the aircraft model. -->
        <xs:element ref="flight_control" minOccurs="0" />
        <!-- The flight control system for the aircraft model. -->
        <xs:element ref="aerodynamics" minOccurs="0" />
        <!-- The aerodynamics definition for the aircraft model. -->
        <xs:element ref="input" minOccurs="0" />
        <!-- The input definition for the aircraft model. -->
        <xs:element ref="output" minOccurs="0" maxOccurs="unbounded" />
        <!--The output specification for the aircraft model. -->
      </xs:sequence>
      <xs:attribute name="name" use="required" type="xs:string">
        <xs:annotation>
          <xs:documentation> The name of the aircraft this model represents. </xs:documentation>
        </xs:annotation>
      </xs:attribute>
      <xs:attribute name="release" use="optional" default="PRODUCTION">
        <xs:annotation>
          <xs:documentation>
            A release type of ALPHA or BETA will print out a warning message explaining
            that this preproduction release may not be of high quality.
          </xs:documentation>
        </xs:annotation>
        <xs:simpleType>
          <xs:restriction base="xs:string">
            <xs:enumeration value="PRODUCTION" />
            <xs:enumeration value="ALPHA" />
            <xs:enumeration value="BETA" />
          </xs:restriction>
        </xs:simpleType>
      </xs:attribute>
      <xs:attribute name="version" use="required">
        <xs:annotation>
          <xs:documentation>Often, the version may initially be simply specified as "\$Revision: 1.29 $", so that
            a configuration management tool such as cvs can automatically generate revision numbers.</xs:documentation>
        </xs:annotation>
        <xs:simpleType>
          <xs:restriction base="xs:string">
            <xs:pattern value="[0-9](.[0-9])*" />
          </xs:restriction>
        </xs:simpleType>
      </xs:attribute>
    </xs:complexType>
  </xs:element>
  <!-- Global Types for this file -->
  <xs:simpleType name="AreaType">
    <xs:restriction base="xs:string">
      <xs:enumeration value="M2" />
      <xs:enumeration value="FT2" />
    </xs:restriction>
  </xs:simpleType>
  <xs:simpleType name="LengthType">
    <xs:restriction base="xs:string">
      <xs:enumeration value="M" />
      <xs:enumeration value="FT" />
      <xs:enumeration value="IN" />
    </xs:restriction>
  </xs:simpleType>
  <xs:simpleType name="InertiaType">
    <xs:restriction base="xs:string">
      <xs:enumeration value="KG*M2" />
      <xs:enumeration value="SLUG*FT2" />
    </xs:restriction>
  </xs:simpleType>
  <xs:simpleType name="WeightType">
    <xs:restriction base="xs:string">
      <xs:enumeration value="KG" />
      <xs:enumeration value="LBS" />
    </xs:restriction>
  </xs:simpleType>
  <xs:simpleType name="SpringCoeffType">
    <xs:restriction base="xs:string">
      <xs:enumeration value="LBS/FT" />
      <xs:enumeration value="N/M" />
    </xs:restriction>
  </xs:simpleType>
  <xs:simpleType name="DampingCoeffType">
    <xs:restriction base="xs:string">
      <xs:enumeration value="LBS/FT/SEC" />
      <xs:enumeration value="N/M/SEC" />
    </xs:restriction>
  </xs:simpleType>
  <xs:simpleType name="AngleType">
    <xs:restriction base="xs:string">
      <xs:enumeration value="DEG" />
      <xs:enumeration value="RAD" />
    </xs:restriction>
  </xs:simpleType>
  <xs:simpleType name="PositiveNumber">
    <xs:restriction base="xs:double">
      <xs:minInclusive value="0" />
    </xs:restriction>
  </xs:simpleType>

  <!-- FILEHEADER ELEMENT -->
  <xs:element name="fileheader">
    <xs:annotation>
      <xs:documentation>The fileheader section is where important information about the model is recorded. The authors, their contact information
      and affiliation, are all documented in this section. Notes about the model, as well as limitations and reference information are also recorded
      in this section.</xs:documentation>
    </xs:annotation>
    <xs:complexType>
      <xs:sequence>
        <xs:choice minOccurs="0" maxOccurs="unbounded">
          <xs:element name="author" type="xs:string">
            <xs:annotation>
              <xs:documentation>The name of the model author[s].</xs:documentation>
            </xs:annotation>
          </xs:element>
          <xs:element name="email" type="xs:string">
            <xs:annotation>
              <xs:documentation>The contact email address for an author (optional).</xs:documentation>
            </xs:annotation>
          </xs:element>
          <xs:element name="organization" type="xs:string">
            <xs:annotation>
              <xs:documentation>The organization that the author[s] belongs to.</xs:documentation>
            </xs:annotation>
          </xs:element>
        </xs:choice>
        <xs:element name="license" minOccurs="0" maxOccurs="1">
          <xs:annotation>
            <xs:documentation>This is an optional field for a license name and URL.</xs:documentation>
          </xs:annotation>
          <xs:complexType>
            <xs:attribute name="licenseName" type="xs:string">
              <xs:annotation>
                <xs:documentation>The name of the license, e.g. "GPL".</xs:documentation>
              </xs:annotation>
            </xs:attribute>
            <xs:attribute name="licenseURL" type="xs:anyURI">
              <xs:annotation>
                <xs:documentation>The URL where the license can be found.</xs:documentation>
              </xs:annotation>
            </xs:attribute>
          </xs:complexType>
        </xs:element>
        <xs:element name="sensitivity" type="xs:string" minOccurs="0" maxOccurs="1">
          <xs:annotation>
            <xs:documentation>This field stores the sensitivity classification, such as "classified", "secret", "proprietary", etc.</xs:documentation>
          </xs:annotation>
        </xs:element>
        <xs:element name="filecreationdate" type="xs:date" minOccurs="0" maxOccurs="1">
          <xs:annotation>
            <xs:documentation>The date that the model was initially created in the form yyyy-mm-dd</xs:documentation>
          </xs:annotation>
        </xs:element>
        <xs:element name="version" type="xs:string" minOccurs="0" maxOccurs="1">
          <xs:annotation>
            <xs:documentation>The version number in the form #.#, or #.#.#, etc. This can also simply be a cvs keyword, such as "\$Revision: 1.29 $".</xs:documentation>
          </xs:annotation>
        </xs:element>
        <xs:element name="copyright" type="xs:string" minOccurs="0" maxOccurs="1">
          <xs:annotation>
            <xs:documentation>Copyright holder(s)</xs:documentation>
          </xs:annotation>
        </xs:element>
        <xs:element name="description" type="xs:string" minOccurs="0" maxOccurs="1">
          <xs:annotation>
            <xs:documentation>A simple text description of the aircraft model.</xs:documentation>
          </xs:annotation>
        </xs:element>
        <xs:choice minOccurs="0" maxOccurs="unbounded">
          <xs:element name="note" type="xs:string">
            <xs:annotation>
              <xs:documentation>Notes are general notes about the model, perhaps such as special information helpful in flying it.</xs:documentation>
            </xs:annotation>
          </xs:element>
          <xs:element name="limitation" type="xs:string">
            <xs:annotation>
              <xs:documentation>Limitations for this model should be noted. For instance, if gear is not aerodynamically modeled.</xs:documentation>
            </xs:annotation>
          </xs:element>
          <xs:element ref="reference">
            <xs:annotation>
              <xs:documentation>All references used in creating this model should be included.</xs:documentation>
            </xs:annotation>
          </xs:element>
        </xs:choice>
      </xs:sequence>
    </xs:complexType>
  </xs:element>
  <xs:element name="reference">
    <xs:annotation>
      <xs:documentation>A reference consists of an author, a publication date, a reference ID (document ID, etc.),
    and of course a title. The title is the only item in a reference that is required.</xs:documentation>
    </xs:annotation>
    <xs:complexType>
      <xs:attribute name="author" use="optional" />
      <xs:attribute name="date" use="optional" />
      <xs:attribute name="refID" use="optional" type="xs:string" />
      <xs:attribute name="title" use="required" />
      <xs:attribute name="URL" use="optional" type="xs:anyURI" />
    </xs:complexType>
  </xs:element>

  <!-- METRICS SECTION -->
  <xs:element name="metrics">
    <xs:annotation>
      <xs:documentation>
        The metrics section holds information about the geometric characteristics of the aircraft that are important
        for the equations of motion and aerodynamics. Wing (or reference) area, wing span (or lateral reference length),
        and wing chord (or longitudinal reference length) are all recorded in this section. The center of graivty is also recorded
        in this section. Units may be given as shown in this section.
      </xs:documentation>
    </xs:annotation>
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="wingarea" />
        <xs:element ref="wingspan" />
        <xs:element ref="wing_incidence" minOccurs="0" />
        <xs:element ref="chord" />
        <xs:element ref="htailarea" minOccurs="0" />
        <xs:element ref="htailarm" minOccurs="0" />
        <xs:element ref="vtailarea" minOccurs="0" />
        <xs:element ref="vtailarm" minOccurs="0" />
        <xs:element ref="location" minOccurs="1" maxOccurs="3" />
      </xs:sequence>
    </xs:complexType>
  </xs:element>
  <!-- Wing Area -->
  <xs:element name="wingarea">
    <xs:annotation>
      <xs:documentation> Wing area (reference area) for the vehicle being modeled. The default unit
        is square feet (FT2). </xs:documentation>
    </xs:annotation>
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base="PositiveNumber">
          <xs:attribute name="unit" use="optional" default="FT2" type="AreaType" />
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>
  <!-- Wing Span -->
  <xs:element name="wingspan">
    <xs:annotation>
      <xs:documentation> Wingspan (lateral reference length) for the vehicle being modeled. The
        default unit is feet (FT). </xs:documentation>
    </xs:annotation>
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base="PositiveNumber">
          <xs:attribute name="unit" use="optional" default="FT" type="LengthType" />
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>
  <!-- Wing Incidence -->
  <xs:element name="wing_incidence">
    <xs:annotation>
      <xs:documentation> The angle the wing makes with the fuselage centerline  for the vehicle being modeled. The default unit
        is degrees (DEG). </xs:documentation>
    </xs:annotation>
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base="xs:double">
          <xs:attribute name="unit" use="optional" default="DEG" type="AngleType" />
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>
  <!-- Wing Chord -->
  <xs:element name="chord">
    <xs:annotation>
      <xs:documentation> Chord (longitudinal reference length) for the vehicle being modeled. The default
        unit is feet (FT). </xs:documentation>
    </xs:annotation>
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base="PositiveNumber">
          <xs:attribute name="unit" use="optional" default="FT" type="LengthType" />
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>
  <!-- Horizontal tail area -->
  <xs:element name="htailarea">
    <xs:annotation>
      <xs:documentation> Horizontal tail area. The default unit is square feet (FT2).</xs:documentation>
    </xs:annotation>
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base="PositiveNumber">
          <xs:attribute name="unit" use="optional" default="FT2" type="AreaType" />
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>
  <!-- Horizontal tail arm -->
  <xs:element name="htailarm">
    <xs:annotation>
      <xs:documentation> Horizontal tail arm. This is the distance from the center of gravity
        to the quarter chord of the horizontal tail. The default unit is feet (FT).</xs:documentation>
    </xs:annotation>
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base="PositiveNumber">
          <xs:attribute name="unit" use="optional" default="FT" type="LengthType" />
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>
  <!-- Vertical tail area -->
  <xs:element name="vtailarea">
    <xs:annotation>
      <xs:documentation> Vertical tail area. The default unit is square feet (FT2).
      </xs:documentation>
    </xs:annotation>
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base="PositiveNumber">
          <xs:attribute name="unit" use="optional" default="FT2" type="AreaType" />
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>
  <!-- Vertical tail arm -->
  <xs:element name="vtailarm">
    <xs:annotation>
      <xs:documentation> Vertical tail arm. The default unit is feet (FT). </xs:documentation>
    </xs:annotation>
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base="PositiveNumber">
          <xs:attribute name="unit" use="optional" default="FT" type="LengthType" />
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>
  
  <!-- MASS BALANCE ELEMENT -->
  <xs:element name="mass_balance">
    <xs:annotation>
      <xs:documentation>Mass properties are specified in this section. The moments of inertia
      are specified first. All of Ixx, Iyy, and Izz are required, in order. The products of inertia are
      not required but, if present, must appear in order Ixy, Ixz, Iyz. Next, the empty weight of
      the aircraft, and the CG location are specified, in that order. Finally, any number of point masses
      can be specified.</xs:documentation>
    </xs:annotation>
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="ixx" minOccurs="1" />
        <xs:element ref="iyy" minOccurs="1" />
        <xs:element ref="izz" minOccurs="1" />
        <xs:element ref="ixy" minOccurs="0" />
        <xs:element ref="ixz" minOccurs="0" />
        <xs:element ref="iyz" minOccurs="0" />
        <xs:element ref="emptywt" minOccurs="1" />
        <xs:element ref="location" minOccurs="1" />
        <xs:element ref="pointmass" minOccurs="0" maxOccurs="unbounded" />
      </xs:sequence>
    </xs:complexType>
  </xs:element>
  <!-- IXX -->
  <xs:element name="ixx">
    <xs:annotation>
      <xs:documentation> Moment of Inertia, Ixx </xs:documentation>
    </xs:annotation>
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base="PositiveNumber">
          <xs:attribute name="unit" use="optional" default="SLUG*FT2" type="InertiaType" />
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>
  <!-- IYY -->
  <xs:element name="iyy">
    <xs:annotation>
      <xs:documentation> Moment of Inertia, Iyy </xs:documentation>
    </xs:annotation>
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base="PositiveNumber">
          <xs:attribute name="unit" use="optional" default="SLUG*FT2" type="InertiaType" />
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>
  <!-- IZZ -->
  <xs:element name="izz">
    <xs:annotation>
      <xs:documentation> Moment of Inertia, Izz </xs:documentation>
    </xs:annotation>
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base="PositiveNumber">
          <xs:attribute name="unit" use="optional" default="SLUG*FT2" type="InertiaType" />
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>
  <!-- IXY -->
  <xs:element name="ixy">
    <xs:annotation>
      <xs:documentation> Moment of Inertia, Ixy </xs:documentation>
    </xs:annotation>
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base="xs:decimal">
          <xs:attribute name="unit" use="optional" default="SLUG*FT2" type="InertiaType" />
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>
  <!-- IXZ -->
  <xs:element name="ixz">
    <xs:annotation>
      <xs:documentation> Moment of Inertia, Ixz </xs:documentation>
    </xs:annotation>
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base="xs:decimal">
          <xs:attribute name="unit" use="optional" default="SLUG*FT2" type="InertiaType" />
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>
  <!-- IYZ -->
  <xs:element name="iyz">
    <xs:annotation>
      <xs:documentation> Moment of Inertia, Iyz </xs:documentation>
    </xs:annotation>
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base="xs:decimal">
          <xs:attribute name="unit" use="optional" default="SLUG*FT2" type="InertiaType" />
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>
  <!-- Empty Weight -->
  <xs:element name="emptywt">
    <xs:annotation>
      <xs:documentation> Empty weight of vehicle. </xs:documentation>
    </xs:annotation>
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base="PositiveNumber">
          <xs:attribute name="unit" use="optional" default="LBS" type="WeightType" />
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>
  <!-- Point Mass -->
  <xs:element name="pointmass">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="weight" />
        <xs:element ref="location" />
      </xs:sequence>
      <xs:attribute name="name" use="required" type="xs:string" />
    </xs:complexType>
  </xs:element>
  <xs:element name="weight">
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base="PositiveNumber">
          <xs:attribute name="unit" use="optional" default="LBS" type="WeightType" />
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>
  <xs:element name="location">
    <xs:annotation>
      <xs:documentation>A location is a vector, containing an x, Y, and Z, element. The default unit is inches (IN). The unit is specifed
      in the unit attribute of the location - not in the individual x, y, or z child elements.</xs:documentation>
    </xs:annotation>
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="x" />
        <xs:element ref="y" />
        <xs:element ref="z" />
      </xs:sequence>
      <xs:attribute name="name" type="xs:string" />
      <xs:attribute name="unit" use="optional" default="IN">
        <xs:simpleType>
          <xs:restriction base="xs:string">
            <xs:enumeration value="M" />
            <xs:enumeration value="FT" />
            <xs:enumeration value="IN" />
          </xs:restriction>
        </xs:simpleType>
      </xs:attribute>
    </xs:complexType>
  </xs:element>
  <xs:element name="direction">
    <xs:annotation>
      <xs:documentation>A direction is a unit vector, containing an x, Y, and Z element which defines
        a direction in a specified frame. </xs:documentation>
    </xs:annotation>
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="x" />
        <xs:element ref="y" />
        <xs:element ref="z" />
      </xs:sequence>
      <xs:attribute name="name" type="xs:string" />
      <xs:attribute name="unit" use="optional" default="IN">
        <xs:simpleType>
          <xs:restriction base="xs:string">
            <xs:enumeration value="M" />
            <xs:enumeration value="FT" />
            <xs:enumeration value="IN" />
          </xs:restriction>
        </xs:simpleType>
      </xs:attribute>
    </xs:complexType>
  </xs:element>
  <xs:element name="x" type="xs:double" />
  <xs:element name="y" type="xs:double" />
  <xs:element name="z" type="xs:double" />

  <!-- Buoyant forces section -->
  <xs:element name="buoyant_forces">
    
  </xs:element>

  <!-- The systems definition -->
  <xs:element name="system">
    <xs:annotation><xs:documentation>
      The system definition can be present any number of times in an aircraft definition. This
      section is used to define an arbitrary system, such as navigation, guidance, or control 
      avionics, electrical systems, etc. The system, autopilot, and flight_control sections of a
      configuration file are all built the same way, using channel elements that contain strings
      of component definitions.
    </xs:documentation></xs:annotation>
    <xs:complexType>
    <xs:choice minOccurs="0" maxOccurs="unbounded">
      <xs:element ref="property" />
      <xs:element ref="sensor" />
      <xs:element ref="channel" />
    </xs:choice>
      <xs:attribute name="name" use="optional" type="xs:string"/>
      <xs:attribute name="file" use="optional" type="xs:string"/>
    </xs:complexType>
  </xs:element>
  
  <!-- AUTOPILOT SECTION -->
  <xs:element name="autopilot">
    <xs:annotation>
      <xs:documentation> The autopilot section is not required for many uses, including for use within Flightgear.
        The autopilot functions can be specified within the autopilot section, or a file name can be given where the 
        autopilot is specified.</xs:documentation>
    </xs:annotation>
    <xs:complexType>
      <xs:sequence>
        <xs:element minOccurs="0" maxOccurs="unbounded" ref="property" />
        <xs:element minOccurs="0" maxOccurs="unbounded" ref="sensor" />
        <xs:element minOccurs="0" maxOccurs="unbounded" ref="channel" />
      </xs:sequence>
      <xs:attribute name="file" type="xs:string" use="optional" />
      <xs:attribute name="name" type="xs:string" use="optional" />
    </xs:complexType>
  </xs:element>
  <!-- FLIGHT CONTROL SECTION -->
  <!-- flight control types -->
  <xs:element name="clipto">
    <xs:annotation>
      <xs:documentation>This element specifies a minimum and/or a maximum limit that the associated component will be allowed
      to have. The result will be clipped to the specified limits.</xs:documentation>
    </xs:annotation>
    <xs:complexType>
      <xs:all>
        <xs:element name="min" type="xs:double" />
        <xs:element name="max" type="xs:double" />
      </xs:all>
    </xs:complexType>
  </xs:element>
  <xs:element name="domain">
    <xs:annotation>
      <xs:documentation>The domain defines the minimum and maximum input value allowed.</xs:documentation>
    </xs:annotation>
    <xs:complexType>
      <xs:all>
        <xs:element name="min" type="xs:float" default="-1" />
        <xs:element name="max" type="xs:float" default="1" />
      </xs:all>
    </xs:complexType>
  </xs:element>
  <xs:element name="range">
    <xs:annotation>
      <xs:documentation>The range defines the minimum and maximum output value mapped..</xs:documentation>
    </xs:annotation>
    <xs:complexType>
      <xs:all>
        <xs:element name="min" type="xs:float" default="0" />
        <xs:element name="max" type="xs:float" default="0" />
      </xs:all>
    </xs:complexType>
  </xs:element>
  <xs:element name="default">
    <xs:complexType>
      <xs:attribute name="value" type="xs:string" />
    </xs:complexType>
  </xs:element>
  <!-- End flight control types -->
  <xs:element name="flight_control">
    <xs:complexType>
      <xs:sequence>
        <xs:element minOccurs="0" maxOccurs="unbounded" ref="property" />
        <xs:element minOccurs="0" maxOccurs="unbounded" ref="sensor" />
        <xs:element minOccurs="0" maxOccurs="unbounded" ref="channel" />
      </xs:sequence>
      <xs:attribute name="file" type="xs:string" use="optional" />
      <xs:attribute name="name" use="optional" type="xs:string" />
    </xs:complexType>
  </xs:element>
  
  <!-- Channel -->
  
  <xs:element name="channel">
    <xs:complexType>
      <xs:choice minOccurs="0" maxOccurs="unbounded">
        <xs:element ref="actuator"/>
        <xs:element ref="aerosurface_scale" />
        <xs:element ref="integrator" />
        <xs:element ref="kinematic" />
        <xs:element ref="lag_filter"/>
        <xs:element ref="lead_lag_filter" />
        <xs:element ref="pid"/>
        <xs:element ref="pure_gain" />
        <xs:element ref="scheduled_gain"/>
        <xs:element ref="second_order_filter" />
        <xs:element ref="sensor"/>
        <xs:element ref="summer" />
        <xs:element ref="switch"/>
        <xs:element ref="washout_filter" />
        <xs:element ref="deadband"/>
        <xs:element ref="fcs_function"/>
      </xs:choice>
      <xs:attribute name="name" use="required" type="xs:string" />
    </xs:complexType>
  </xs:element>
  
  <!-- Lag filter -->
  
  <xs:element name="lag_filter">
    <xs:complexType>
      <xs:all>
        <xs:element name="description" type="xs:string" minOccurs="0"/>
        <xs:element name="input" type="xs:string" maxOccurs="1" minOccurs="1" />
        <xs:element name="c1" type="xs:double" minOccurs="1" maxOccurs="1" />
        <xs:element ref="clipto" minOccurs="0" maxOccurs="1" />
        <xs:element name="output" type="xs:string" minOccurs="0" maxOccurs="1" />
      </xs:all>
      <xs:attribute name="name" use="required" type="xs:string" />
    </xs:complexType>
  </xs:element>
  
  <!-- Summer -->
  
  <xs:element name="summer">
    <xs:complexType>
      <xs:sequence>
        <xs:element name="description" type="xs:string" minOccurs="0"/>
        <xs:element name="input" type="xs:string" maxOccurs="unbounded"/>
        <xs:element name="bias" type="xs:float" minOccurs="0"/>
        <xs:element ref="clipto" minOccurs="0"/>
        <xs:element name="output" minOccurs="0" type="xs:string" />
      </xs:sequence>
      <xs:attribute name="name" use="required" type="xs:string" />
    </xs:complexType>
  </xs:element>
  
  <!-- Aerosurface scale -->
  
  <xs:element name="aerosurface_scale">
    <xs:annotation>
      <xs:documentation>
        The aerosurface scale component maps an input value (which must fall within the span specified in the domain element)
        to an output value that falls within the span specified in the range element. For example, if the actual input value is 30% of
        the distance from the minimum to the maximum domain value, the output would be the value corresponding
        to 30% of the span of the range, from the minimum range value.
      </xs:documentation>
    </xs:annotation>
    <xs:complexType>
      <xs:all>
        <xs:element name="description" type="xs:string" minOccurs="0"/>
        <xs:element name="input" type="xs:string" minOccurs="1" maxOccurs="1" />
        <xs:element ref="domain" minOccurs="0" maxOccurs="1" />
        <xs:element ref="range" minOccurs="1" maxOccurs="1" />
        <xs:element name="gain" minOccurs="0" maxOccurs="1">
          <xs:annotation>
            <xs:documentation>The Gain element may contain a fixed numeric value, or it may be a property name.</xs:documentation>
          </xs:annotation>
        </xs:element>
        <xs:element ref="clipto" minOccurs="0" maxOccurs="1" />
        <xs:element name="output" minOccurs="0" maxOccurs="1" type="xs:string" />
      </xs:all>
      <xs:attribute name="name" use="required" type="xs:string" />
    </xs:complexType>
  </xs:element>
  
  <!-- Kinematic device -->
  
  <xs:element name="kinematic">
    <xs:complexType>
      <xs:all>
        <xs:element name="description" type="xs:string" minOccurs="0"/>
        <xs:element name="input" type="xs:string" minOccurs="1" maxOccurs="1" />
        <xs:element ref="traverse" />
        <xs:element ref="clipto" minOccurs="0" maxOccurs="1" />
        <xs:element name="output" minOccurs="0" maxOccurs="1" type="xs:string" />
      </xs:all>
      <xs:attribute name="name" use="required" type="xs:string" />
    </xs:complexType>
  </xs:element>
  <xs:element name="traverse">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="setting" minOccurs="1" maxOccurs="unbounded" />
      </xs:sequence>
    </xs:complexType>
  </xs:element>
  <xs:element name="setting">
    <xs:complexType>
      <xs:sequence>
        <xs:element name="position" type="xs:double" />
        <xs:element name="time" type="xs:double" />
      </xs:sequence>
    </xs:complexType>
  </xs:element>
  
  <!-- Lead lag filter -->
  
  <xs:element name="lead_lag_filter">
    <xs:complexType>
      <xs:all>
        <xs:element name="description" type="xs:string" minOccurs="0"/>
        <xs:element name="input" type="xs:string" minOccurs="1" maxOccurs="1" />
        <xs:element name="c1" type="xs:double" />
        <xs:element name="c2" type="xs:double" minOccurs="0" />
        <xs:element name="c3" type="xs:double" minOccurs="0" />
        <xs:element name="c4" type="xs:double" />
        <xs:element ref="clipto" minOccurs="0" maxOccurs="1" />
        <xs:element name="output" minOccurs="0" maxOccurs="1" type="xs:string" />
      </xs:all>
      <xs:attribute name="name" use="required" type="xs:string" />
    </xs:complexType>
  </xs:element>
  
  <!-- Washout filter -->
  
  <xs:element name="washout_filter">
    <xs:complexType>
      <xs:all>
        <xs:element name="description" type="xs:string" minOccurs="0"/>
        <xs:element name="input" type="xs:string" maxOccurs="1" minOccurs="1" />
        <xs:element name="c1" type="xs:double" minOccurs="1" maxOccurs="1" />
        <xs:element ref="clipto" minOccurs="0" maxOccurs="1" />
        <xs:element name="output" type="xs:string" minOccurs="0" maxOccurs="1" />
      </xs:all>
      <xs:attribute name="name" use="required" type="xs:string" />
    </xs:complexType>
  </xs:element>
  
  <!-- Integrator -->
  
  <xs:element name="integrator">
    <xs:complexType>
      <xs:all>
        <xs:element name="description" type="xs:string" minOccurs="0"/>
        <xs:element name="input" type="xs:string" maxOccurs="1" minOccurs="1" />
        <xs:element name="c1" type="xs:double" minOccurs="1" maxOccurs="1" />
        <xs:element ref="clipto" minOccurs="0" maxOccurs="1" />
        <xs:element name="output" type="xs:string" minOccurs="0" maxOccurs="1" />
        <xs:element name="trigger" type="xs:string" minOccurs="0" maxOccurs="1" />
      </xs:all>
      <xs:attribute name="name" use="required" type="xs:string" />
    </xs:complexType>
  </xs:element>
  
  <!-- PID controller -->
  
  <xs:element name="pid">
    <xs:complexType>
      <xs:all>
        <xs:element name="description" type="xs:string" minOccurs="0"/>
        <xs:element name="input" type="xs:string" minOccurs="1" maxOccurs="1" />
        <xs:element name="kp" type="xs:float" minOccurs="0"/>
        <xs:element name="ki" type="xs:float" minOccurs="0"/>
        <xs:element name="kd" type="xs:float" minOccurs="0"/>
        <xs:element name="trigger" type="xs:string" minOccurs="0"/>
        <xs:element ref="clipto" minOccurs="0" maxOccurs="1" />
        <xs:element name="output" minOccurs="0" maxOccurs="1" type="xs:string" />
      </xs:all>
      <xs:attribute name="name" type="xs:string" use="required"/>
    </xs:complexType>
  </xs:element>
  <!-- Second order filter -->
  
  <xs:element name="second_order_filter">
    <xs:complexType>
      <xs:all>
        <xs:element name="description" type="xs:string" minOccurs="0"/>
        <xs:element name="input" type="xs:string" minOccurs="1" maxOccurs="1" />
        <xs:element name="c1" type="xs:double" />
        <xs:element name="c2" type="xs:double" />
        <xs:element name="c3" type="xs:double" />
        <xs:element name="c4" type="xs:double" />
        <xs:element name="c5" type="xs:double" />
        <xs:element name="c6" type="xs:double" />
        <xs:element ref="clipto" minOccurs="0" maxOccurs="1" />
        <xs:element name="output" minOccurs="0" maxOccurs="1" type="xs:string" />
      </xs:all>
      <xs:attribute name="name" use="required" type="xs:string" />
    </xs:complexType>
  </xs:element>
  
  <!-- Pure gain -->
  
  <xs:element name="pure_gain">
    <xs:complexType>
      <xs:all>
        <xs:element name="description" type="xs:string" minOccurs="0"/>
        <xs:element name="input" type="xs:string" minOccurs="1" maxOccurs="1" />
        <xs:element name="gain" type="xs:string" minOccurs="1" maxOccurs="1">
          <xs:annotation>
            <xs:documentation>The Gain element may contain a fixed numeric value, or it may be a property name.</xs:documentation>
          </xs:annotation>
        </xs:element>
        <xs:element ref="clipto" minOccurs="0" maxOccurs="1" />
        <xs:element name="output" minOccurs="0" maxOccurs="1" type="xs:string" />
      </xs:all>
      <xs:attribute name="name" use="required" type="xs:string" />
    </xs:complexType>
  </xs:element>
  
  <!-- Scheduled gain -->
  
  <xs:element name="scheduled_gain">
    <xs:complexType>
      <xs:all>
        <xs:element name="description" type="xs:string" minOccurs="0"/>
        <xs:element name="input" type="xs:string" minOccurs="1" maxOccurs="1" />
        <xs:element ref="table" minOccurs="1" maxOccurs="1" />
        <xs:element name="gain" type="xs:string" minOccurs="0" maxOccurs="1">
          <xs:annotation>
            <xs:documentation>The Gain element may contain a fixed numeric value, or it may be a property name.</xs:documentation>
          </xs:annotation>
        </xs:element>
        <xs:element ref="clipto" minOccurs="0" />
        <xs:element name="output" minOccurs="0" />
      </xs:all>
      <xs:attribute name="name" use="required" type="xs:string" />
    </xs:complexType>
  </xs:element>
  
  <!-- Switch -->
  
  <xs:element name="switch">
    <xs:complexType>
      <xs:sequence>
        <xs:element name="description" type="xs:string" minOccurs="0"/>
        <xs:element name="input" type="xs:string" minOccurs="0" />
        <xs:element ref="default" minOccurs="0" />
        <xs:element ref="test" minOccurs="1" maxOccurs="unbounded" />
        <xs:element ref="clipto" minOccurs="0" />
        <xs:element name="output" minOccurs="0" />
      </xs:sequence>
      <xs:attribute name="name" use="required" type="xs:string" />
    </xs:complexType>
  </xs:element>
  
  <!-- Sensor -->
  
  <xs:element name="sensor">
    <xs:complexType>
      <xs:sequence>
        <xs:element name="description" type="xs:string" minOccurs="0"/>
        <xs:element name="input" type="xs:string" maxOccurs="1"/>
        <xs:element name="lag" type="xs:float" maxOccurs="1"/>        
        <xs:element ref="noise" maxOccurs="1"/>
        <xs:element ref="quantization" maxOccurs="1"/>
        <xs:element name="drift_rate" type="xs:float" maxOccurs="1"/>
        <xs:element name="bias" type="xs:float" maxOccurs="1" />
        <xs:element ref="clipto" maxOccurs="1"/>
        <xs:element name="output" maxOccurs="1"/>
      </xs:sequence>
      <xs:attribute name="name" use="required" type="xs:string" />
    </xs:complexType>
  </xs:element>

  <!-- Actuator -->
  
  <xs:element name="actuator">
    <xs:annotation>
      <xs:documentation>
        An actuator component models a general purpose mechanical effector. The actuator can
        exhibit a lag, can be rate- and position-limited, can feature a bias, can have a deadband,
        and it can feature hysteresis.
      </xs:documentation>
    </xs:annotation>
    <xs:complexType>
      <xs:all>
        <xs:element name="description" type="xs:string" minOccurs="0"/>
        <xs:element name="input" minOccurs="1" type="xs:string" />
        <xs:element name="lag" type="xs:float" minOccurs="0"/>
        <xs:element name="rate_limit" type="xs:float" minOccurs="0"/>
        <xs:element name="bias" type="xs:float" minOccurs="0"/>
        <xs:element name="deadband_width" type="xs:float" minOccurs="0"/>
        <xs:element name="hysteresis_width" type="xs:float" minOccurs="0"/>
        <xs:element ref="clipto" minOccurs="0"/>
        <xs:element name="output" minOccurs="0" type="xs:string" />
      </xs:all>
      <xs:attribute name="name" use="required" type="xs:string" />
    </xs:complexType>
  </xs:element>

  <!-- Deadband -->
  
  <xs:element name="deadband">
    <xs:complexType>
      <xs:all>
        <xs:element name="description" type="xs:string" minOccurs="0"/>
        <xs:element name="input" type="xs:string"/>
        <xs:element name="width" type="xs:float"/>
        <xs:element ref="clipto" minOccurs="0"/>
        <xs:element name="output" minOccurs="0" type="xs:string" />
      </xs:all>
      <xs:attribute name="name" use="required" type="xs:string" />
    </xs:complexType>
  </xs:element>

  <!-- FCS function -->
  <xs:element name="fcs_function">
    <xs:complexType>
      <xs:all>
        <xs:element name="input" type="xs:string" minOccurs="0"/>
        <xs:element ref="description" minOccurs="0"/>
        <xs:element ref="function"/>
        <xs:element ref="clipto" minOccurs="0"/>
        <xs:element name="output" minOccurs="0" type="xs:string" />
      </xs:all>
      <xs:attribute name="name" use="required" type="xs:string" />
    </xs:complexType>
    
  </xs:element>

  <!--

  <xs:group name="functionGroup">
    <xs:sequence>
      <xs:element ref="input"/>
      <xs:element name="function"/>
    </xs:sequence>
  </xs:group>

  <xs:group name="deadbandGroup">
    <xs:sequence>
      <xs:element ref="input"/>
      <xs:element ref="width"/>
    </xs:sequence>
  </xs:group>
 
-->
  <xs:element name="test">
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base="xs:string">
          <xs:attribute name="logic" default="AND" use="optional">
            <xs:simpleType>
              <xs:restriction base="xs:string">
                <xs:enumeration value="OR" />
                <xs:enumeration value="AND" />
              </xs:restriction>
            </xs:simpleType>
          </xs:attribute>
          <xs:attribute name="value" use="required" type="xs:string" />
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>
  <xs:element name="width" type="PositiveNumber">
    <xs:annotation>
      <xs:documentation>The width value specifies the width of the deadband - i.e. 
        the total span about zero where the input will be mapped to zero output.</xs:documentation>
    </xs:annotation>
  </xs:element>
  
  <xs:element name="noise">
    <xs:annotation>
      <xs:documentation>
        The noise can be entered as a percentage of the signal, or as an absolute value.        
      </xs:documentation>
    </xs:annotation>
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base="xs:float">
          <xs:attribute name="variation">
            <xs:simpleType>
              <xs:restriction base="xs:string">
                <xs:enumeration value="PERCENT"/>
                <xs:enumeration value="ABSOLUTE"/>
              </xs:restriction>
            </xs:simpleType>
          </xs:attribute>
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>

  <xs:element name="quantization">
    <xs:complexType>
      <xs:all>
        <xs:element name="bits" type="xs:int"/>
        <xs:element name="min" type="xs:float"/>
        <xs:element name="max" type="xs:float"/>
      </xs:all>
      <xs:attribute type="xs:string" name="name"/>
    </xs:complexType>
  </xs:element>

  <!-- AERODYNAMICS SECTION -->
  <xs:element name="aerodynamics">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="alphalimits" minOccurs="0" />
        <xs:element ref="hysteresis_limits" minOccurs="0" />
        <xs:element ref="function" minOccurs="0" maxOccurs="unbounded" />
        <xs:element ref="axis" minOccurs="0" maxOccurs="6" />
      </xs:sequence>
    </xs:complexType>
  </xs:element>
  <xs:element name="alphalimits">
    <xs:complexType>
      <xs:sequence>
        <xs:element name="min" type="xs:double" />
        <xs:element name="max" type="xs:double" />
      </xs:sequence>
      <xs:attribute name="unit" use="optional" type="AngleType" default="DEG" />
    </xs:complexType>
  </xs:element>
  <xs:element name="hysteresis_limits">
    <xs:complexType>
      <xs:sequence>
        <xs:element name="min" type="xs:double" />
        <xs:element name="max" type="xs:double" />
      </xs:sequence>
      <xs:attribute name="unit" use="optional" type="AngleType" default="DEG" />
    </xs:complexType>
  </xs:element>
  <xs:element name="axis">
    <xs:complexType>
      <xs:sequence>
        <xs:element maxOccurs="unbounded" ref="function" />
      </xs:sequence>
      <xs:attribute name="name" use="required" type="xs:string" />
    </xs:complexType>
  </xs:element>
  <xs:element name="description" type="xs:string" />

  <!--EXTERNAL REACTIONS SECTION -->
  <xs:element name="external_reactions">
    <xs:complexType>
      <xs:sequence>
        <xs:element minOccurs="0" maxOccurs="unbounded" ref="property" />
        <xs:element minOccurs="0" maxOccurs="unbounded" ref="force" />
      </xs:sequence>
      <xs:attribute name="file" use="optional" type="xs:string" />
    </xs:complexType>
  </xs:element>

  <xs:element name="force">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="function" minOccurs="0"/>
        <xs:element ref="location"/>
        <xs:element ref="direction" minOccurs="0"/>
      </xs:sequence>
      <xs:attribute name="name" type="xs:string"/>      
      <xs:attribute name="frame">
          <xs:simpleType>
            <xs:restriction base="xs:string">
              <xs:enumeration value="BODY"/>
              <xs:enumeration value="LOCAL"/>
              <xs:enumeration value="WIND"/>
            </xs:restriction>
          </xs:simpleType>
      </xs:attribute>
    </xs:complexType>
  </xs:element>
  
  <!--GROUND REACTIONS SECTION -->
  <xs:element name="ground_reactions">
    <xs:complexType mixed="true">
      <xs:sequence>
        <xs:element minOccurs="0" maxOccurs="unbounded" ref="contact" />
      </xs:sequence>
    </xs:complexType>
  </xs:element>
  
  <xs:element name="contact">
    <xs:complexType>
      <xs:all>
        <xs:element ref="location" />
        <xs:element name="static_friction" type="xs:double" />
        <xs:element name="dynamic_friction" type="xs:double" />
        <xs:element name="spring_coeff">
          <xs:complexType>
            <xs:simpleContent>
              <xs:extension base="PositiveNumber">
                <xs:attribute name="unit" use="optional" default="LBS/FT" type="SpringCoeffType" />
              </xs:extension>
            </xs:simpleContent>
          </xs:complexType>
        </xs:element>
        <xs:element name="damping_coeff">
          <xs:complexType>
            <xs:simpleContent>
              <xs:extension base="PositiveNumber">
                <xs:attribute name="unit" use="optional" default="LBS/FT/SEC" type="DampingCoeffType" />
              </xs:extension>
            </xs:simpleContent>
          </xs:complexType>
        </xs:element>
        <xs:element name="damping_coeff_rebound" minOccurs="0">
          <xs:complexType>
            <xs:simpleContent>
              <xs:extension base="PositiveNumber">
                <xs:attribute name="unit" use="optional" default="LBS/FT/SEC" type="DampingCoeffType" />
              </xs:extension>
            </xs:simpleContent>
          </xs:complexType>
        </xs:element>
        <xs:element name="rolling_friction" type="xs:double" minOccurs="0" />
        <xs:element name="max_steer" minOccurs="0">
          <xs:complexType>
            <xs:simpleContent>
              <xs:extension base="PositiveNumber">
                <xs:attribute name="unit" use="optional" default="DEG" type="AngleType" />
              </xs:extension>
            </xs:simpleContent>
          </xs:complexType>
        </xs:element>
        <xs:element ref="brake_group" minOccurs="0" />
        <xs:element ref="retractable" minOccurs="0" />
        <xs:element name="relaxation_velocity" minOccurs="0">
          <xs:complexType>
            <xs:sequence>
              <xs:sequence>
                <xs:element name="rolling">
                  <xs:complexType>
                    <xs:simpleContent>
                      <xs:extension base="xs:float">
                        <xs:attribute name="unit" default="FT/SEC" use="optional" />
                      </xs:extension>
                    </xs:simpleContent>
                  </xs:complexType>
                </xs:element>
                <xs:element name="side">
                  <xs:complexType>
                    <xs:simpleContent>
                      <xs:extension base="xs:float">
                        <xs:attribute name="unit" default="FT/SEC" use="optional" />
                      </xs:extension>
                    </xs:simpleContent>
                  </xs:complexType>
                </xs:element>
              </xs:sequence>
            </xs:sequence>
          </xs:complexType>
        </xs:element>
        <xs:element ref="force_lag_filter" minOccurs="0"/>
        <xs:element name="wheel_slip_filter" type="xs:float" minOccurs="0"/>
      </xs:all>
      <xs:attribute name="name" use="required" type="xs:string" />
      <xs:attribute name="type" use="required">
        <xs:simpleType>
          <xs:restriction base="xs:string">
            <xs:enumeration value="BOGEY" />
            <xs:enumeration value="STRUCTURE" />
          </xs:restriction>
        </xs:simpleType>
      </xs:attribute>
    </xs:complexType>
  </xs:element>
  
  <xs:element name="brake_group" type="xs:NCName" />
  <xs:element name="retractable" type="xs:integer" />
  
  <xs:element name="force_lag_filter">
    <xs:complexType>
      <xs:all>
        <xs:element name="rolling" type="xs:float" maxOccurs="1"/>
        <xs:element name="side" type="xs:float" maxOccurs="1"/>
      </xs:all>
    </xs:complexType>
  </xs:element>
  
  <!-- PROPULSION SECTION -->
  <xs:element name="propulsion">
    <xs:complexType>
      <xs:sequence>
        <xs:element name="property" maxOccurs="unbounded" minOccurs="0">
          <xs:complexType mixed="true">
            <xs:attribute name="value" use="optional" type="xs:double"/>
          </xs:complexType>
        </xs:element>
        <xs:choice maxOccurs="unbounded">
          <xs:element ref="engine"/>
          <xs:element ref="tank"/>
        </xs:choice>
      </xs:sequence>
    </xs:complexType>
  </xs:element>
  <xs:element name="engine">
    <xs:complexType>
      <xs:sequence>
        <xs:element name="description" type="xs:string" minOccurs="0"/>
        <xs:element maxOccurs="unbounded" ref="feed" />
        <xs:element ref="thruster" />
      </xs:sequence>
      <xs:attribute name="file" use="required" type="xs:string" />
    </xs:complexType>
  </xs:element>
  <xs:element name="feed" type="xs:integer" />
  <xs:element name="thruster">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="location" />        
        <xs:choice>
          <xs:element ref="orient"/>
          <xs:element ref="pointing"/>
        </xs:choice>
        <xs:element ref="sense" minOccurs="0" />
        <xs:element ref="p_factor" minOccurs="0" />
      </xs:sequence>
      <xs:attribute name="file" use="required" type="xs:string" />
    </xs:complexType>
  </xs:element>
  <xs:element name="sense" type="xs:integer" />
  <xs:element name="p_factor" type="xs:decimal" />
  <xs:element name="tank">
    <xs:complexType>
      <xs:all>
        <xs:element minOccurs="0" name="priority" type="xs:double"/>
        <xs:element name="temperature" type="xs:double" minOccurs="0" />
        <xs:element ref="location" minOccurs="1" />
        <xs:element ref="radius" minOccurs="0" />
        <xs:element name="inertia_factor" type="xs:double" minOccurs="0"/>
        <xs:element ref="capacity" minOccurs="0" />
        <xs:element ref="standpipe" minOccurs="0" />
        <xs:element ref="contents" minOccurs="0" />
        <xs:element ref="drain_location" minOccurs="0" />
      </xs:all>
      <xs:attribute name="type" use="required" type="xs:string" />
      <xs:attribute name="number" use="optional" type="xs:integer" />
    </xs:complexType>
  </xs:element>
  <xs:element name="radius">
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base="xs:double">
          <xs:attribute name="unit" use="required" type="xs:NCName" />
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>
  <xs:element name="capacity">
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base="xs:double">
          <xs:attribute name="unit" use="required" type="xs:NCName" />
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>
  <xs:element name="standpipe">
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base="xs:double">
          <xs:attribute name="unit" use="required" type="xs:NCName" />
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>
  <xs:element name="contents">
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base="xs:double">
          <xs:attribute name="unit" use="required" type="xs:string" />
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>
  <xs:element name="drain_location">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="x"/>
        <xs:element ref="y"/>
        <xs:element ref="z"/>
      </xs:sequence>
      <xs:attribute name="unit" use="required" type="xs:NCName"/>
    </xs:complexType>
  </xs:element>
  <!-- INPUT SECTION -->
  <xs:element name="input">
    <xs:complexType mixed="true">
      <xs:attribute name="port" type="xs:integer" />
    </xs:complexType>
  </xs:element>
  <!--
  <xs:element name="min" type="xs:decimal"/>
  <xs:element name="max" type="xs:decimal"/>
-->
  <!-- OUTPUT SECTION -->
  <xs:element name="output">
    <xs:complexType>
      <xs:choice maxOccurs="3">
        <xs:sequence minOccurs="0" maxOccurs="unbounded">
          <xs:element name="property" minOccurs="0" maxOccurs="unbounded">
            <xs:complexType>
              <xs:simpleContent>
                <xs:extension base="xs:string">
                  <xs:attribute name="caption" type="xs:string"/>
                </xs:extension>
              </xs:simpleContent>
            </xs:complexType>
          </xs:element>
        </xs:sequence>
        <xs:sequence minOccurs="0">
          <xs:element name="simulation" type="xs:string" minOccurs="0" />
          <xs:element name="atmosphere" type="xs:string" minOccurs="0" />
          <xs:element name="massprops" type="xs:string" minOccurs="0" />
          <xs:element name="rates" type="xs:string" minOccurs="0" />
          <xs:element name="velocities" type="xs:string" minOccurs="0" />
          <xs:element name="forces" type="xs:string" minOccurs="0" />
          <xs:element name="moments" type="xs:string" minOccurs="0" />
          <xs:element name="position" type="xs:string" minOccurs="0" />
          <xs:element name="propulsion" type="xs:string" minOccurs="0" />
          <xs:element name="aerosurfaces" type="xs:string" minOccurs="0" />
          <xs:element name="fcs" type="xs:string" minOccurs="0" />
          <xs:element name="ground_reactions" type="xs:string" minOccurs="0" />
          <xs:element name="coefficients" type="xs:string" minOccurs="0" />
        </xs:sequence>
      </xs:choice>
      <xs:attribute name="name" type="xs:string" />
      <xs:attribute name="port" type="xs:integer" />
      <xs:attribute name="rate" type="xs:integer" />
      <xs:attribute name="type">
        <xs:simpleType>
          <xs:restriction base="xs:string">
            <xs:enumeration value="CSV" />
            <xs:enumeration value="TABULAR" />
            <xs:enumeration value="SOCKET" />
            <xs:enumeration value="NONE" />
          </xs:restriction>
        </xs:simpleType>
      </xs:attribute>
    </xs:complexType>
  </xs:element>
  <!-- Functions -->
  <xs:group name="func_group">
    <xs:choice>
      <xs:element ref="table" />
      <xs:element ref="product" />
      <xs:element ref="difference" />
      <xs:element ref="sum" />
      <xs:element ref="quotient" />
      <xs:element ref="pow" />
      <xs:element ref="abs" />
      <xs:element ref="sin" />
      <xs:element ref="cos" />
      <xs:element ref="tan" />
      <xs:element ref="asin" />
      <xs:element ref="acos" />
      <xs:element ref="atan" />
      <xs:element ref="atan2" />
      <xs:element ref="min" />
      <xs:element ref="max" />
      <xs:element ref="avg" />
      <xs:element ref="fraction" />
      <xs:element ref="integer" />
      <xs:element ref="mod"/>
      <xs:element name="random"/>
      <xs:element name="urandom"/>
      <xs:element name="pi"/>
      <!--xs:element ref="rotation_alpha_local" /-->
      <!--xs:element ref="rotation_beta_local" /-->
      <!--xs:element ref="rotation_gamma_local" /-->
      <!--xs:element ref="rotation_bf_to_wf" /-->
      <!--xs:element ref="rotation_wf_to_bf" /-->
      <xs:element ref="lt" />
      <xs:element ref="le" />
      <xs:element ref="gt" />
      <xs:element ref="ge" />
      <xs:element ref="eq" />
      <xs:element ref="nq" />
      <xs:element ref="and" />
      <xs:element ref="or" />
      <xs:element ref="not" />
      <xs:element ref="ifthen" />
      <xs:element name="switch">
        <xs:complexType>
          <xs:choice minOccurs="2" maxOccurs="unbounded">
            <xs:group ref="func_group" />
            <xs:element ref="value" />
            <xs:element ref="property" />
          </xs:choice>
        </xs:complexType>
     </xs:element>
      <xs:element ref="interpolate1d" />
    </xs:choice>
  </xs:group>
  <xs:element name="function">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="description" minOccurs="0"/>
        <xs:group ref="func_group" />
      </xs:sequence>
      <xs:attribute name="name" use="optional" />
    </xs:complexType>
  </xs:element>
  <xs:element name="product">
    <xs:complexType>
      <xs:choice maxOccurs="unbounded">
        <xs:group ref="func_group" />
        <xs:element ref="value" />
        <xs:element ref="property" />
      </xs:choice>
    </xs:complexType>
  </xs:element>
  <xs:element name="difference">
    <xs:complexType>
      <xs:choice maxOccurs="2">
        <xs:group ref="func_group" />
        <xs:element ref="value" />
        <xs:element ref="property" />
      </xs:choice>
    </xs:complexType>
  </xs:element>
  <xs:element name="sum">
    <xs:complexType>
      <xs:choice maxOccurs="unbounded">
        <xs:group ref="func_group" />
        <xs:element ref="value" />
        <xs:element ref="property" />
      </xs:choice>
    </xs:complexType>
  </xs:element>
  <xs:element name="quotient">
    <xs:complexType>
      <xs:choice maxOccurs="2">
        <xs:group ref="func_group" />
        <xs:element ref="value" />
        <xs:element ref="property" />
      </xs:choice>
    </xs:complexType>
  </xs:element>
  <xs:element name="abs">
    <xs:complexType>
      <xs:choice maxOccurs="1" minOccurs="1">
        <xs:group ref="func_group" />
        <xs:element ref="value" />
        <xs:element ref="property" />
      </xs:choice>
    </xs:complexType>
  </xs:element>
  <xs:element name="pow">
    <xs:complexType>
      <xs:choice maxOccurs="2" minOccurs="2">
        <xs:group ref="func_group" />
        <xs:element ref="value" />
        <xs:element ref="property" />
      </xs:choice>
    </xs:complexType>
  </xs:element>
  <xs:element name="sin">
    <xs:complexType>
      <xs:choice maxOccurs="1" minOccurs="1">
        <xs:group ref="func_group" />
        <xs:element ref="value" />
        <xs:element ref="property" />
      </xs:choice>
    </xs:complexType>
  </xs:element>
  <xs:element name="cos">
    <xs:complexType>
      <xs:choice maxOccurs="1" minOccurs="1">
        <xs:group ref="func_group" />
        <xs:element ref="value" />
        <xs:element ref="property" />
      </xs:choice>
    </xs:complexType>
  </xs:element>
  <xs:element name="tan">
    <xs:complexType>
      <xs:choice maxOccurs="1" minOccurs="1">
        <xs:group ref="func_group" />
        <xs:element ref="value" />
        <xs:element ref="property" />
      </xs:choice>
    </xs:complexType>
  </xs:element>
  <xs:element name="asin">
    <xs:complexType>
      <xs:choice maxOccurs="1" minOccurs="1">
        <xs:group ref="func_group" />
        <xs:element ref="value" />
        <xs:element ref="property" />
      </xs:choice>
    </xs:complexType>
  </xs:element>
  <xs:element name="acos">
    <xs:complexType>
      <xs:choice maxOccurs="1" minOccurs="1">
        <xs:group ref="func_group" />
        <xs:element ref="value" />
        <xs:element ref="property" />
      </xs:choice>
    </xs:complexType>
  </xs:element>
  <xs:element name="atan">
    <xs:complexType>
      <xs:choice maxOccurs="1" minOccurs="1">
        <xs:group ref="func_group" />
        <xs:element ref="value" />
        <xs:element ref="property" />
      </xs:choice>
    </xs:complexType>
  </xs:element>
  <xs:element name="atan2">
    <xs:complexType>
      <xs:choice maxOccurs="2" minOccurs="2">
        <xs:group ref="func_group" />
        <xs:element ref="value" />
        <xs:element ref="property" />
      </xs:choice>
    </xs:complexType>
  </xs:element>
  <xs:element name="min">
    <xs:complexType>
      <xs:choice maxOccurs="unbounded">
        <xs:group ref="func_group" />
        <xs:element ref="value" />
        <xs:element ref="property" />
      </xs:choice>
    </xs:complexType>
  </xs:element>
  <xs:element name="max">
    <xs:complexType>
      <xs:choice maxOccurs="unbounded">
        <xs:group ref="func_group" />
        <xs:element ref="value" />
        <xs:element ref="property" />
      </xs:choice>
    </xs:complexType>
  </xs:element>
  <xs:element name="avg">
    <xs:complexType>
      <xs:choice minOccurs="2" maxOccurs="unbounded">
        <xs:group ref="func_group" />
        <xs:element ref="value" />
        <xs:element ref="property" />
      </xs:choice>
    </xs:complexType>
  </xs:element>
  <xs:element name="fraction">
    <xs:complexType>
      <xs:choice>
        <xs:group ref="func_group" />
        <xs:element ref="value" />
        <xs:element ref="property" />
      </xs:choice>
    </xs:complexType>
  </xs:element>
  <xs:element name="integer">
    <xs:complexType>
      <xs:choice>
        <xs:group ref="func_group" />
        <xs:element ref="value" />
        <xs:element ref="property" />
      </xs:choice>
    </xs:complexType>
  </xs:element>
  <xs:element name="value" type="xs:double" />

  <xs:element name="mod">
    <xs:complexType>
      <xs:choice maxOccurs="2" minOccurs="2">
        <xs:group ref="func_group" />
        <xs:element ref="value" />
        <xs:element ref="property" />
      </xs:choice>
    </xs:complexType>
  </xs:element>
  <xs:element name="lt">
    <xs:complexType>
      <xs:choice maxOccurs="2" minOccurs="2">
        <xs:group ref="func_group" />
        <xs:element ref="value" />
        <xs:element ref="property" />
      </xs:choice>
    </xs:complexType>
  </xs:element>
  <xs:element name="le">
    <xs:complexType>
      <xs:choice maxOccurs="2" minOccurs="2">
        <xs:group ref="func_group" />
        <xs:element ref="value" />
        <xs:element ref="property" />
      </xs:choice>
    </xs:complexType>
  </xs:element>
  <xs:element name="gt">
    <xs:complexType>
      <xs:choice maxOccurs="2" minOccurs="2">
        <xs:group ref="func_group" />
        <xs:element ref="value" />
        <xs:element ref="property" />
      </xs:choice>
    </xs:complexType>
  </xs:element>
  <xs:element name="ge">
    <xs:complexType>
      <xs:choice maxOccurs="2" minOccurs="2">
        <xs:group ref="func_group" />
        <xs:element ref="value" />
        <xs:element ref="property" />
      </xs:choice>
    </xs:complexType>
  </xs:element>
  <xs:element name="eq">
    <xs:complexType>
      <xs:choice maxOccurs="2" minOccurs="2">
        <xs:group ref="func_group" />
        <xs:element ref="value" />
        <xs:element ref="property" />
      </xs:choice>
    </xs:complexType>
  </xs:element>
  <xs:element name="nq">
    <xs:complexType>
      <xs:choice maxOccurs="2" minOccurs="2">
        <xs:group ref="func_group" />
        <xs:element ref="value" />
        <xs:element ref="property" />
      </xs:choice>
    </xs:complexType>
  </xs:element>
  <xs:element name="and">
    <xs:complexType>
      <xs:choice minOccurs="2" maxOccurs="unbounded">
        <xs:group ref="func_group" />
        <xs:element ref="value" />
        <xs:element ref="property" />
      </xs:choice>
    </xs:complexType>
  </xs:element>
  <xs:element name="or">
    <xs:complexType>
      <xs:choice minOccurs="2" maxOccurs="unbounded">
        <xs:group ref="func_group" />
        <xs:element ref="value" />
        <xs:element ref="property" />
      </xs:choice>
    </xs:complexType>
  </xs:element>
  <xs:element name="not">
    <xs:complexType>
      <xs:choice minOccurs="1" maxOccurs="1">
        <xs:group ref="func_group" />
        <xs:element ref="value" />
        <xs:element ref="property" />
      </xs:choice>
    </xs:complexType>
  </xs:element>
  <xs:element name="ifthen">
    <xs:complexType>
      <xs:choice minOccurs="3" maxOccurs="3">
        <xs:group ref="func_group" />
        <xs:element ref="value" />
        <xs:element ref="property" />
      </xs:choice>
    </xs:complexType>
  </xs:element>
  <xs:element name="interpolate1d">
    <xs:complexType>
      <xs:choice minOccurs="3" maxOccurs="unbounded">
        <xs:group ref="func_group" />
        <xs:element ref="value" />
        <xs:element ref="property" />
      </xs:choice>
    </xs:complexType>
  </xs:element>
  <xs:element name="orient">
    <xs:complexType>
      <xs:all>
        <xs:element ref="roll" minOccurs="0" />
        <xs:element ref="pitch" minOccurs="0" />
        <xs:element ref="yaw" minOccurs="0" />
      </xs:all>
      <xs:attribute name="unit" use="required" type="xs:string" />
    </xs:complexType>
  </xs:element>
  <xs:element name="pointing">
    <xs:annotation><xs:documentation>
      The pointing element is an alternative to the use of the orient element. With the pointing
      element, a unit vector is supplied that represents the direction that the thruster force vector acts
      in. The pointing vector is defined in the structural frame.
    </xs:documentation></xs:annotation>
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="x"/>
        <xs:element ref="y"/>
        <xs:element ref="z"/>
      </xs:sequence>
    </xs:complexType>
  </xs:element>
  <xs:element name="roll" type="xs:double" />
  <xs:element name="pitch" type="xs:double" />
  <xs:element name="yaw" type="xs:double" />
  <xs:element name="property" type="xs:string" />
  <xs:element name="table">
    <xs:complexType>
      <xs:sequence>
        <xs:element maxOccurs="unbounded" ref="independentVar" />
        <xs:element ref="tableData" minOccurs="1" maxOccurs="unbounded" />
      </xs:sequence>
      <xs:attribute name="name" use="optional" type="xs:string" />
    </xs:complexType>
  </xs:element>
  <xs:element name="independentVar">
    <xs:complexType mixed="true">
      <xs:attribute name="lookup" type="xs:string" />
    </xs:complexType>
  </xs:element>
  <xs:element name="tableData">
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base="xs:string">
          <xs:attribute name="breakPoint" type="xs:double" use="optional" />
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>
</xs:schema>