Why is the Sign Up Stamp important in Space-R procedures?

The Sign Up Stamp is important in Space-R procedures because it serves as an official proof of registration. This stamp indicates that a passenger has properly registered for a flight or travel option under the Space-Available program. By providing this proof, it ensures that there is a clear record of who is eligible for boarding based on their registration status. This documentation is essential for maintaining an orderly check-in and boarding process, especially when dealing with limited seating and prioritization criteria inherent in Space-R procedures.

Other options may highlight aspects of the travel experience, such as boarding expediency, priority access, or overall satisfaction, but they do not encapsulate the fundamental purpose of the Sign Up Stamp, which is to validate that passengers have correctly completed the necessary registration steps to be considered for available seating.