PNRBooking-class (RBD) letters, explained by cabin and airline
The single letter after a flight number decides what the passenger paid for and, roughly, where they sit. But the same letter can mean different things on different airlines — here's how to read it without being caught out.
Every ticket carries a Reservation Booking Designator (RBD) — one letter that identifies the fare bucket the seat was sold in. It is the first character of the fare basis and the letter you see in the segment line. It does two jobs: it signals the cabin (First, Business, Premium Economy, Economy) and it identifies the specific fare bucket within that cabin, which governs the price and the rules.
The common convention
A handful of letters are near-universal, which is why a general table is a useful starting point:
| Cabin | Typical letters |
|---|---|
| First | F, A |
| Business | J, C, D, I, Z |
| Premium Economy | W, E, O, R, S (varies widely) |
| Economy | Y, B, H, K, M, L, V, S, N, Q, T, X, G, O, U |
Y is the classic full-fare economy letter; J the full-fare business letter; F full-fare first. From there, each cabin has a ladder of discounted buckets, and this is where airlines diverge.
Why the same letter differs by airline
RBDs are set by each carrier individually. The letters in the middle and at the edges of the alphabet get reused for whatever a given airline needs. Three concrete examples:
- W and E are Premium Economy on Emirates, but on plenty of other carriers
WandEare simply discounted Economy buckets. Read the same letter on the wrong airline and you will over- or under-state the cabin. - R is First class on a few carriers, but on Qatar Airways
Ris a Business-class fare ("Business Classic"), and on others it is Premium Economy. It is one of the most overloaded letters in the alphabet. - P is a discounted First bucket on some North-American carriers, but a Premium Economy or Business bucket elsewhere.
How PNRpro handles this
PNRpro maps class letters to cabins using the common convention as a baseline, then applies per-airline overrides for carriers whose lettering is known to differ — so an Emirates W reads as Premium Economy while a generic W reads as Economy, and a Qatar R reads as Business rather than First. You can also override the cabin on any segment by hand before you generate the itinerary, which is the right move whenever you have the fare basis in front of you and want to be certain.
Award and special buckets
Some letters are reserved for award (redemption) inventory rather than cash fares — for instance a carrier may sell economy awards in X and business awards in U or I. These still map to a cabin, but the letter tells you it was a miles booking, which can matter for changes and eligibility. If a letter looks out of place for the cabin you expect, an award bucket is a likely explanation.