DTD for RoCKit:
<!-- This is a DTD for RoCKit Data -->
<!ELEMENT Element_Definitions (Comment?, Elements)>
<!ATTLIST Element_Definitions version CDATA #REQUIRED creator CDATA #REQUIRED name CDATA #REQUIRED>
  <!ELEMENT Comment (#PCDATA)>
  <!ELEMENT Elements (Light | Element | Group)*>
    <!ELEMENT Light (Comment?, (Ambient_Light | Directional_Light | Point_Light), ColorRGB)>
    <!ATTLIST Light name CDATA #REQUIRED state (on|off) "on">
      <!ELEMENT Ambient_Light EMPTY>
      <!ELEMENT Directional_Light (Vector3D)>
      <!ELEMENT Point_Light (Point3D, Attenuation?)>
        <!ELEMENT Attenuation EMPTY>
        <!ATTLIST Attenuation constant CDATA #REQUIRED linear CDATA #REQUIRED quadratic CDATA #REQUIRED>
    <!ELEMENT Element (Comment?, Geometry, Transformation3D?, Appearance?, Actors?, Sensors?)>
    <!ATTLIST Element name CDATA #REQUIRED>
      <!ELEMENT Geometry (Cylinder | Box | Sphere | ... | (Geometry_Coordinates, Geometry_Normals, Texture_Coordinates, Geometry_Colors))>
        <!ELEMENT Cylinder EMPTY>
	<!ELEMENT Box EMPTY>
	<!ELEMENT Sphere EMPTY>
    <!ELEMENT Group (Comment?, Transformation3D?, Elements, Actors?, Sensors?)>
    <!ATTLIST Group name CDATA #REQUIRED>

<!-- common definitions for groups and elements with geometric aspects (e.g. Cylinder, Box, Sphere, ...) -->
<!ELEMENT Transformation3D (Rotation3D?, Vector3D?, Scale3D?)>
  <!ELEMENT Rotation3D EMPTY>
  <!ATTLIST Rotation3D a11 CDATA #REQUIRED a12 CDATA #REQUIRED a13 CDATA #REQUIRED
                       a21 CDATA #REQUIRED a22 CDATA #REQUIRED a23 CDATA #REQUIRED
                       a31 CDATA #REQUIRED a32 CDATA #REQUIRED a33 CDATA #REQUIRED>
  <!ELEMENT Scale3D EMPTY>
  <!ATTLIST Scale3D CDATA #REQUIRED y CDATA #REQUIRED z CDATA #REQUIRED>
<!ELEMENT Appearance ((Color, Material) | Color)>
  <!ELEMENT Color (Color_RGB)>
  <!ELEMENT Material (Ambient_Color, Emissive_Color, Diffuse_Color, Specular_Color)>
    <!ELEMENT Ambient_Color (Color_RGB)>
    <!ELEMENT Emissive_Color (Color_RGB)>
    <!ELEMENT Diffuse_Color (Color_RGB)>
    <!ELEMENT Specular_Color (Color_RGB)>
<!ELEMENT Actors (Rotation_Motor*, Translation_Motor*, Display*)>
  <!ELEMENT Rotation_Motor EMPTY>
  <!ATTLIST Rotation_Motor name CDATA #REQUIRED rpm_min CDATA #REQUIRED rpm_max CDATA #REQUIRED>
  <!ELEMENT Translation_Motor (Vector3D, Vector3D)>
  <!ATTLIST Translation_Motor name CDATA #REQUIRED mmps_min CDATA #REQUIRED mmps_max CDATA #REQUIRED>
  <!ELEMENT Display EMPT)>
  <!ATTLIST Display name CDATA #REQUIRED rows CDATA #REQUIRED columns CDATA #REQUIRED>
<!ELEMENT Sensors (Bumper*, Lightsensor*, IR_Sensor*, Camera*)>
  <!ELEMENT Bumper (Transformation3D?)>
  <!ATTLIST Bumper name CDATA #REQUIRED sensibility_angle CDATA #REQUIRED>
  <!ELEMENT Light_Sensor (Transformation3D?, Light_Sensibility)>
  <!ATTLIST Light_Sensor name CDATA #REQUIRED>
    <!ELEMENT Light_Sensibility (Sensibility_Factor+)>
      <!ELEMENT Sensibility_Factor EMPTY>
      <!ATTLIST Sensibility_Factor angle CDATA #REQUIRED factor CDATA #REQUIRED>
  <!ELEMENT IR_Sensor (Transformation3D?, IR_Sensibility)>
  <!ATTLIST IR_Sensor name CDATA #REQUIRED>
    <!ELEMENT IR_Sensibility (Sensibility_Distance+)>
      <!ELEMENT Sensibility_Distance EMPTY>
      <!ATTLIST Sensibility_Distance angle CDATA #REQUIRED distance CDATA #REQUIRED>
  <!ELEMENT Camera (Transformation3D?)>
  <!ATTLIST Camera name CDATA #REQUIRED x_res CDATA #REQUIRED x_res CDATA #REQUIRED field_of_view CDATA #REQUIRED>

<!-- common definitions (used in different elements) -->
<!ELEMENT Color_RGB EMPTY>
<!ATTLIST Color_RGN red CDATA #REQUIRED green CDATA #REQUIRED blue CDATA #REQUIRED>
<!ELEMENT Vector3D EMPTY>
<!ATTLIST Vector3D x CDATA #REQUIRED y CDATA #REQUIRED z CDATA #REQUIRED>
<!ELEMENT Point3D EMPTY>
<!ATTLIST Point3D x CDATA #REQUIRED y CDATA #REQUIRED z CDATA #REQUIRED>



Example RoCKit-XML-File:
<?xml version="1.0"?>
<Element_Definitions version="1.0" creator="RoCKit V1.0" name="Football Robots">
	<Comment>
		In this library of elements you can find definitions for various Robots specially designed for playing football.
		To complete this compilation there are also some definitions for footballs.
	</Comment>
	<Elements>
		<Element name="Diego Maradona">
			<Geometry> <Box/> </Geometry>
			<Transformation3D>
				<Vector3D x="10.0" y="15.0" z="21.5"/>
				<Scale3D x="25.0" y="0.02" z="7.0"/>
			</Transformation3D>
			<Appearance face="left">
				<Color> <Color_RGB r="0.1" g="0.1" b="0.1"/> </Color>
			</Appearance>
		</Element>
		<Group name="Toni Polster">
			<Comment> This Robot is a good striker. </Comment>
			<Transformation3D></Transformation3D>      <!-- legt eine TransforGroup mit Identity-Transformation an --->
			<Elements>
				<Element name="body">
					<Geometry> <Cylinder/> </Geometry>
					<Transformation3D>
						<Vector3D x="10.0" y="15.0" z="21.5"/>
						<Scale3D x="10.0" y="10.0" z="15.0"/>
					</Transformation3D>
					<Appearance>
						<Color> <Color_RGB r="1.0" g="0.0" b="0.0"/> </Color>
						<Material lighting="enabled" shininess="64">
							<Ambient_Color>  <Color_RGB r="1.0" g="0.0" b="0.0"/> </Ambient_Color>
							<Emissive_Color> <Color_RGB r="1.0" g="0.0" b="0.0"/> </Emissive_Color>
							<Diffuse_Color>  <Color_RGB r="1.0" g="0.0" b="0.0"/> </Diffuse_Color>
							<Specular_Color> <Color_RGB r="1.0" g="0.0" b="0.0"/> </Specular_Color>
						</Material>
					</Appearance>
				</Element>
				<Element name="left wheel>
					<Geometry> <Cylinder/> </Geometry>
					<Transformation3D>
						...
					</Transformation3D>
					<Appearance>
						...
					</Appearance>
					<Actors>
						<Rotation_Motor name="motor" rpm_min="-100" rpm_max="2300"/>
						<Translation_Motor name="translate" mmps_min="-10" mmps_max="20">
							<Vector3D x="0.0" y="0.0" z="0.0"/>
							<Vector3D x="10.0" y="0.0" z="0.0"/>
						</Translation_Motor>	
					</Actors>
				</Element>
				<Element name="right wheel>
					...
				</Element>
			</Elements>
			<Actors>
				<Display name="messages" rows="2" columns="40"/>
			</Actors>
			<Sensors>
				<Bumper name="front" sensibility_angle="0.9">
					<Transformation3D>       die x-Achse des lokalen Koordinatensystems gibt die Richtung der Empfindlichkeit an!?!?
						<Rotation3D
						  a11="1.0"  a12="-1.0" a13="0.0"
						  a21="-1.0" a22="1.0"  a23="0.0"
						  a31="0.0"  a32="0.0"  a33="1.0" 
						/>
						<Vector3D x="10.0" y="15.0" z="21.5"/>
					</Transformation3D>
				</Bumper>
				<Light_Sensor name="top">
					<Transformation3D>       die x-Achse des lokalen Koordinatensystems gibt die Richtung der Empfindlichkeit an!?!?
						<Rotation3D
						  a11="1.0"  a12="-1.0" a13="0.0"
						  a21="-1.0" a22="1.0"  a23="0.0"
						  a31="0.0"  a32="0.0"  a33="1.0" 
						/>
						<Vector3D x="10.0" y="15.0" z="21.5"/>
					</Transformation3D>
					<Light_Sensibility>
						<Sensibility_Factor angle="-1.0" factor="0.0"/>
						<Sensibility_Factor angle="-0.5" factor="0.7"/>
						<Sensibility_Factor angle="0.0"  factor="1.0"/>
						<Sensibility_Factor angle="0.5"  factor="0.7"/>
						<Sensibility_Factor angle="1.0"  factor="0.0"/>
					</Light_Sensibility>
				</Light_Sensor>
				<IR_Sensor name="front-left">
					<Transformation3D>       die x-Achse des lokalen Koordinatensystems gibt die Richtung der Empfindlichkeit an!!!!
						<Rotation3D
						  a11="1.0"  a12="-1.0" a13="0.0"
						  a21="-1.0" a22="1.0"  a23="0.0"
						  a31="0.0"  a32="0.0"  a33="1.0" 
						/>
						<Vector3D x="10.0" y="15.0" z="21.5"/>
					</Transformation3D>
					<IR_Sensibility>
						<Sensibility_Distance angle="-0.7" distance="5.0"/>
						<Sensibility_Distance angle="0.7"  distance="5.0"/>
					</IR_Sensibility>
				</IR_Sensor>
				<Camera name="left eye" x_res="640" y_res="480" field_of_view="1.0">
				</Camera>
			</Sensors>
		</Group>
		<Element name="world cup ball">
			<Geometry> <Sphere/> </Geometry>
			<Transformation3D>
				<Scale3D x="5.0" y="5.0" z="5.0"/>
			</Transformation3D>
		</Element>
	</Elements>
</Element_Definitions>