<launch>                <!-- root tag -->
<node>                  <!-- node and parameters to start -->
<include>               <!-- include another launch file -->
<machine>               <!-- target machine -->
<env-loader>            <!-- set environment variables -->
<param>                 <!-- define a parameter on the parameter server -->
<rosparam>              <!-- load YAML parameters into the parameter server -->
<arg>                   <!-- define an argument -->
<remap>                 <!-- set topic remapping -->
<group>                 <!-- set a group -->
</launch>               <!-- root tag -->
