Try Combined Communications Electronics Board (CCEB) doc. ACP-131, which is the controlling document for Q- and Z- codes; they certainly used to be (1990s) repeated in ICAO 8400-4, and, iirc, 6100... I haven't had cause to check for a loooong while.
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A 2009 copy of ACP-131(F) can be found
here. Q- codes are in Chap. 2, Sec. A. QNE is defined on p. 2-20.
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One suspects that the erroneous use was once taught by person A, who taught person B .... etc. until person N wrote a manual and it became
a thing.