When pluralizing a hyphenated acronym, where does the "s" land in the acronym? [duplicate]

Solution 1:

The most sensible approach, I think, is to put the -s at the end of the acronym/initialism that it pluralizes. Punctuation aside, I see no essential difference between "Transportation Rail Specialist - Explosives (TRS-E)" and "Transportation Rail Specialist for Explosives (TRSE)"—and I assume that you would not argue in favor of "TRSsE" as the plural form of "TRSE."

Bryan Garner, Garner's Modern American Usage, fourth edition (2016) has a useful comment with regard to assigning plurals to initialisms such as POW and WMD:

As with POW and WMD, even if the first word is the main noun in the spelled-out form (prisoner of war, weapon of mass destruction), and the spelled out version would pluralize that noun (prisoners of war, weapons of mass destruction), the abbreviated plural is nevertheless formed with -s at the end of the abbreviation (POWs, WMDs). A few writers mistakenly use the singular form as if the plural form were internally understood—e.g.: "With it comes the end, I hope, of the hoopla and parades of the three POW {read POWs} that wandered aimlessly into enemy territory and were taken prisoner for a few days." [Citation omitted.]

Garner is principally concerned here with what he considers the error of dropping the -s altogether when the whole word that would have been pluralized if the phrase had been rendered in full corresponds to a letter in the initialism other than the final one. But Garner's narrow focus on that particular issue strongly suggests that very few writers have been inclined to render the plurals of POW and WMD as, respectively, PsOW and WsMD.

The inclusion of a hyphen in the initialism TRS-E doesn't alter the fundamental reasonableness of the idea that the -s used to pluralize an initialism should follow the last letter of the initialism, and that the initialism in that case—whether rendered as TRS-E or as TRSE—ends at the E, not the S.