Common XODE extensions:



1. File path for 3D meshes

	<ext name="mesh-file-location">
	    <location>./data/models/tire-small.3ds</location>
	</ext>
	
2. Colour attribute for objects

	<ext name="colour">
	    <colour r="255" g="0" b="0 />
	</ext>

	or

	<ext name="colour">
	    <colour hextriplet="CCCCCC" />
	</ext>

3. Breakable Joints - Roel van Dijk

<!-- inside the properties tag of a joint tag -->
<ext>
	<extension name="breakable-joint">
		<!-- Break condition for the first body connected to the joint. -->
		<breakcondition body="1">
			<!-- Breaks at a certain force, NOT at a certain torque. -->
			<force x="1.5" y="1.5" z="1.5"/>
		</breakcondition>

		<!-- Break condition for the second body connected to the joint. -->
		<breakcondition body="2">
			<!-- Breaks at a certain torque, NOT at a certain force. -->
			<torque x="1.0" y="1.0" z="1.0"/>
		</breakcondition>

		<!-- Not sure about this, but a breakable joint can have a callback
		      function that is called when the joint breaks. -->
		<callback name="bla"/>
	</extension>
</ext>

Having this extension inside the properties of a joint makes it a breakable 
joint. Having a break condition for a body implies that the joint can break 
where it is attached to that body. A force tag implies that the joint can 
break at a certain force but only if there is a force tag. If the force tag 
is omitted then the joint won't break under any force.