I'm using ROS Lunar and Gazebo 7.0.

I'm trying to use "libgazeborosdiff_drive.so" plugin with a Pioneer2DX. I'm new on this, so I'm following the tutorial Controlling a differential drive robot in Gazebo from ROS.

The plugin configuration is this:

<plugin name='differential_drive_controller'
              filename='libgazebo_ros_diff_drive.so'>
        <alwaysOn>true</alwaysOn>
        <updateRate>100</updateRate>
        <leftJoint>left_wheel_hinge</leftJoint>
        <rightJoint>right_wheel_hinge</rightJoint>
        <wheelSeparation>0.39</wheelSeparation>
        <wheelDiameter>0.15</wheelDiameter>
        <torque>5</torque>
        <commandTopic>cmd_vel</commandTopic>
        <odometryTopic>odom</odometryTopic>
        <odometryFrame>odom</odometryFrame>
        <robotBaseFrame>chassis</robotBaseFrame>
      </plugin>

I know there is a page where all of this configuration is explained but I can't find it!!!

Where can I find the description of all of those configuration settings?