FIFA Futsal Laws of the Game

The reserve assistant referee:

• is appointed under the competition rules and replaces the timekeeper if any of the referees is unable to continue officiating the match. He assists the referees at all times 
• assists with any administrative duties before, during and after the match, as required by the referees
• after the match, he submits a report to the appropriate authorities on any misconduct or other incident that occurred out of the view of the referees. He must advise the referees of any report being made
• records all incidents occurring before, during and after the match
• carries an alternative manual chronometer in case it is required due to an incident of any kind
• is situated in a prominent place, but not next to the assistant referees