Fabric relies on XML plans to define workflows. A plan is submitted either from a file or through the /fabric/set_plan service as raw XML text.

The current XML parser accepts only these element types:

<Plan> as the document root.
<Control> with a required type attribute.
<Runner> with required interface and provider attributes.

Supported control types are:

sequential
parallel_any
parallel_all
recovery

Any additional attributes on a <Runner> are forwarded into the runner's EventParameters and are auto-typed as bool, int, double, or string.

Below is a valid example plan shape:

<?xml version='1.0' encoding='UTF-8'?>
<Plan name='example_plan'>
  <Control type='sequential' name='main_execution'>
    <Runner interface='capabilities2_runner_nav2/WaypointRunner' provider='capabilities2_runner_nav2/WaypointRunner' x='5.0' y='5.0' />
 
    <Control type='parallel_any' name='gather_context'>
      <Runner interface='capabilities2_runner_nav2/RobotPoseRunner' provider='capabilities2_runner_nav2/RobotPoseRunner' from='map' to='base_link' />
      <Runner interface='capabilities2_runner_nav2/OccupancyGridRunner' provider='capabilities2_runner_nav2/OccupancyGridRunner' />
    </Control>
 
    <Control type='recovery' name='return_home_on_failure'>
      <Runner interface='capabilities2_runner_nav2/WaypointRunner' provider='capabilities2_runner_nav2/WaypointRunner' x='0.0' y='0.0' />
      </Control>
  </Control>
</Plan>

Notes:

You do not need to include a completion runner manually. The parser appends fabric_capabilities/FabricCompletionRunner automatically and injects the generated plan_id.
A plan submitted through /fabric/set_plan only gets a lightweight XML compatibility check up front. Full syntax validation happens during parsing.