What does “PAX” mean on a Qatar Airways flight ticket?

Question

Example (mirror, mirror 2):

What does "PAX" mean on a Qatar Airways flight ticket?

Typically, PAX=passenger, but in that case I don't understand why the ticket says "passenger" there.

Answer 1

Short answer: PAX=passenger, and the ticket says "passenger" there because the entire line "PAX /C1-4 NON END/CHNG PENALTIES AS PER RULE" was copied from the Amadeus program (which mentions PAX).

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Looking at the Amadeus training manual (Jan. 2012), the PAX line comes from Amadeus:

and PAX means passenger:

Additionally, Locutus_WPC mentioned on Reddit:

In this context PAX probably refers to an adult passenger. Would’ve said CHD or INF if describing a child or infant fare.