IATA calls the EMD its official standard document for optional and ancillary services. It works like an e-ticket: a document is issued, the customer gets a receipt and the value coupons are stored electronically in the airline’s system. The standard is set out in IATA resolutions 725f, 725g and 725h.

Two types

• EMD-A (associated). Linked to an e-ticket and used with it. Aegean, for example, issues EMD-As for extra baggage and for seats.

• EMD-S (standalone). Used independently of a ticket. Aegean issues one for its group penalty fee.

IATA’s BSP manual says accredited agents can issue EMDs as well as e-tickets through their ticketing systems, and both are reported through BSP. IATA’s 2010 implementation guide described EMDs as the electronic replacement for paper documents such as the miscellaneous charges order (MCO) and excess baggage tickets. Each EMD carries a reason for issuance code (C, for example, means baggage) and a sub-code for the specific service.

Worth knowing

• Each airline sets its own rules. Aegean, for example, says an unused EMD is valid for one year from issue and can only be exchanged for the same service sub-code. Its excess baggage EMDs are non-refundable in voluntary cases, such as when the passenger decides not to use the extra bags.

• Mistakes are charged back. An airline can raise an agency debit memo on an EMD transaction, as it can on a ticket.

• Changes ahead. IATA’s ONE Order programme aims to phase out PNRs, e-tickets and EMDs gradually, combining them into a single order record.