What does a 'passenger extra' designation imply about a train?

The designation of 'passenger extra' primarily indicates that the train is carrying passengers but does not adhere to the regular schedule of service. This typically means that the train may operate on an irregular basis, possibly as a supplemental service to accommodate additional passenger demand or special circumstances. This designation allows for flexibility in scheduling, which can be particularly useful during peak travel times, events, or emergencies where more capacity for passengers is required. Understanding this term is important for the effective management of rail operations, ensuring that both regular and additional passenger services can be accurately coordinated and communicated.