Booking airline tickets for international flights

While e-ticket itinerary receipts may at first glance look like a basic itinerary, they contain a number of other features that distingish them.
E-tickets, like their paper counterparts, will contain an official ticket number (including the airline's 3-digit code, a 4-digit form number, a 6-digit serial number, and sometimes a check digit).
Carriage terms and conditions, (or at least a reference to them)
Fare and tax details, including fare calculation details and some additional data such as tour codes. The exact cost might not be stated, but a "fare basis" code will always identify the fare used.
A short summary of fare restrictions, usually specifying only whether change or refund are permitted but not the penalties to which they are subject.
Form of payment.
Issuing office.
Baggage allowance.