We have three sorts of Marshals at the worlds.
The regular marshal
These marshals will be looking for rule infringements (Kneeling on turned feet, Pistols grips on the ground etc) and making scoring car alterations etc.
Then we have Chief marshals.
These marshal do the same as a regular marshal, however, they will also be issued a target checker and will have the responsibility of checking targets.
Then there is the senior chief marshal,
These marshal will do the same as the previous two, but they will also make the decision as to whether a target needs to be changed over.
They are also there to make a final decision if it is required.
All marshals will get a letter when they book in, within this letter will be a brief outline of their duties.
Hope this helps
Here are the rules