JSBSimSystem.xsd

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">

  <!-- 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 name="description" type="xs:string" minOccurs="0"/>
        <xs:element name="property">
          <xs:complexType>
            <xs:simpleContent>
              <xs:extension base="xs:string">
                <xs:attribute name="value" use="optional" type="xs:double"/>
              </xs:extension>
            </xs:simpleContent>
          </xs:complexType>
        </xs:element>
        <xs:element minOccurs="0" maxOccurs="unbounded" 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>

  <!-- Channel -->

  <xs:element name="channel">
    <xs:complexType>
      <xs:choice minOccurs="0" maxOccurs="unbounded">
        <xs:element name="description" type="xs:string" minOccurs="0"/>
        <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"/>
        <xs:element name="c1" type="xs:double"/>
        <xs:element ref="clipto" minOccurs="0" maxOccurs="1"/>
        <xs:element name="output" type="xs:string" minOccurs="0"/>
      </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" maxOccurs="unbounded"/>
      </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:choice maxOccurs="unbounded">
        <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="unbounded" type="xs:string"/>
      </xs:choice>
      <xs:attribute name="name" use="required" type="xs:string"/>
    </xs:complexType>
  </xs:element>

  <!-- Kinematic device -->

  <xs:element name="kinematic">
    <xs:complexType>
      <xs:sequence>
        <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="unbounded" type="xs:string"/>
      </xs:sequence>
      <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:sequence>
        <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="unbounded" type="xs:string"/>
      </xs:sequence>
      <xs:attribute name="name" use="required" type="xs:string"/>
    </xs:complexType>
  </xs:element>

  <!-- Washout filter -->

  <xs:element name="washout_filter">
    <xs:complexType>
      <xs:sequence>
        <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="unbounded"/>
      </xs:sequence>
      <xs:attribute name="name" use="required" type="xs:string"/>
    </xs:complexType>
  </xs:element>

  <!-- Integrator -->

  <xs:element name="integrator">
    <xs:complexType>
      <xs:sequence>
        <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="trigger" type="xs:string" minOccurs="0" maxOccurs="1"/>
        <xs:element name="output" type="xs:string" minOccurs="0" maxOccurs="unbounded"/>
      </xs:sequence>
      <xs:attribute name="name" use="required" type="xs:string"/>
    </xs:complexType>
  </xs:element>

  <!-- PID controller -->

  <xs:element name="pid">
    <xs:complexType>
      <xs:sequence>
        <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="unbounded" type="xs:string"/>
      </xs:sequence>
      <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:sequence>
        <xs:element name="description" type="xs:string" minOccurs="0"/>
        <xs:element name="input" type="xs:string"/>
        <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="unbounded" type="xs:string"/>
      </xs:sequence>
      <xs:attribute name="name" use="required" type="xs:string"/>
    </xs:complexType>
  </xs:element>

  <!-- Pure gain -->

  <xs:element name="pure_gain">
    <xs:complexType>
      <xs:sequence>
        <xs:element name="description" type="xs:string" minOccurs="0"/>
        <xs:element name="input" type="xs:string"/>
        <xs:element name="gain" type="xs:string">
          <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="unbounded" type="xs:string"/>
      </xs:sequence>
      <xs:attribute name="name" use="required" type="xs:string"/>
    </xs:complexType>
  </xs:element>

  <!-- Scheduled gain -->

  <xs:element name="scheduled_gain">
    <xs:complexType>
      <xs:sequence>
        <xs:element name="description" type="xs:string" minOccurs="0"/>
        <xs:element name="input" type="xs:string"/>
        <xs:element ref="table"/>
        <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" maxOccurs="unbounded"/>
      </xs:sequence>
      <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" maxOccurs="unbounded"/>
      </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" minOccurs="0" maxOccurs="unbounded"/>
      </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:sequence>
        <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" maxOccurs="unbounded" type="xs:string"/>
      </xs:sequence>
      <xs:attribute name="name" use="required" type="xs:string"/>
    </xs:complexType>
  </xs:element>

  <!-- Deadband -->

  <xs:element name="deadband">
    <xs:complexType>
      <xs:sequence>
        <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" maxOccurs="unbounded" type="xs:string"/>
      </xs:sequence>
      <xs:attribute name="name" use="required" type="xs:string"/>
    </xs:complexType>
  </xs:element>

  <!-- FCS function -->
  <xs:element name="fcs_function">
    <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="function"/>
        <xs:element ref="clipto" minOccurs="0"/>
        <xs:element name="output" minOccurs="0" maxOccurs="unbounded" type="xs:string"/>
      </xs:sequence>
      <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>

  <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>

  <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>

  <!-- 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:choice>
  </xs:group>
  <xs:element name="function">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="description" minOccurs="0" maxOccurs="1"/>
        <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:element name="v"/>
        <xs:element name="p"/>
      </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:element name="v"/>
        <xs:element name="p"/>
      </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:element name="v"/>
        <xs:element name="p"/>
      </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:element name="v"/>
        <xs:element name="p"/>
      </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:element name="v"/>
        <xs:element name="p"/>
      </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:element name="v"/>
        <xs:element name="p"/>
      </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:element name="v"/>
        <xs:element name="p"/>
      </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:element name="v"/>
        <xs:element name="p"/>
      </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:element name="v"/>
        <xs:element name="p"/>
      </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:element name="v"/>
        <xs:element name="p"/>
      </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:element name="v"/>
        <xs:element name="p"/>
      </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:element name="v"/>
        <xs:element name="p"/>
      </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:element name="v"/>
        <xs:element name="p"/>
      </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:element name="v"/>
        <xs:element name="p"/>
      </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:element name="v"/>
        <xs:element name="p"/>
      </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:element name="v"/>
        <xs:element name="p"/>
      </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:element name="v"/>
        <xs:element name="p"/>
      </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:element name="v"/>
        <xs:element name="p"/>
      </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:element name="v"/>
        <xs:element name="p"/>
      </xs:choice>
    </xs:complexType>
  </xs:element>
  <xs:simpleType name="PositiveNumber">
    <xs:restriction base="xs:double">
      <xs:minInclusive value="0"/>
    </xs:restriction>
  </xs:simpleType>

  <xs:element name="property" type="xs:string"/>
  <xs:element name="description" type="xs:string">
    <xs:annotation>
      <xs:documentation>A simple text description of the item.</xs:documentation>
    </xs:annotation>
  </xs:element>
</xs:schema>