Final answer:
CSTID under the 'Cruise' header could be a specific identifier used by a cruise company, potentially for traveler, ship identification, or booking reference, but the exact meaning is unclear without further context.
Step-by-step explanation:
The term "CSTID" under the header "Cruise" could refer to various things since it's not a commonly known abbreviation in the public domain. In the context of cruising or cruise lines, CSTID might be a specific identifier used by a company for traveler identification, ship identification, or as a booking reference number. However, without the specific context or information from the cruise line, it's challenging to provide a definite answer to what "CSTID" means. It's best to consult the documentation provided by the cruise line or contact their customer service for an accurate explanation.