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Finnair sells "ticket types" instead of booking classes. The various ticket types can overlap in booking class, but they differ in service level and fare terms.
The ticket types are not sold on destinations covered by joint ventures, ie Japan and NA.

Economy tickets:
Light: Z, O, Q, N, S, V, L
Basic: Z, O, Q, N, S, V, L
Value: Z, O, Q, N, S, V, L, K, M
Pro: Y, B, H

[P, T, R and W Economy class fares have been removed in April 2019 in preparation for the launch of Premium Economy in 2021.]
https://www.flyertalk.com/forum/finn...-2021-a-2.html

Premium Economy (from 2021):
P, T, R, W

Business Saver: I (long-haul)
Business: J, C, D (and I for shorthaul in Europe)


Economy award: X
Premium economy award & upgraded: F
Business award & upgraded: U

Light is a handbag-only fare, currently only offered in shorthaul operations (Europe and Middle East).
In addition to the above six fare families there is one additional ticket type called “Saver”, which contains restricted starting-from fares in the lowest booking classes in fares from Asia and North America.

For deeper insights, see this user guide link