<!--VIRTUAL JOINT: Purpose: this element defines a virtual joint between a robot link and an external frame of reference (considered fixed with respect to the robot)-->
<!--VIRTUAL JOINT: Purpose: this element defines a virtual joint between a robot link and an external frame of reference (considered fixed with respect to the robot)-->
<!--DISABLE COLLISIONS: By default it is assumed that any link of the robot could potentially come into collision with any other link in the robot. This tag disables collision checking between a specified pair of links. -->
<!--DISABLE COLLISIONS: By default it is assumed that any link of the robot could potentially come into collision with any other link in the robot. This tag disables collision checking between a specified pair of links. -->