Not sure if it’s used a lot in English, but in French a « valeur étalon » is a value of reference. Like you measure something precisely, define it as standard and it becomes your étalon for future measures
I guess it’s used in this sense here
I guess it’s used in this sense here
Is it said in a neutral sense like yardstick or is it an ideal to aspire to like exemplar or paragon?
You can see here a kilogramme étalon: https://upload.wikimedia.org/wikipedia/commons/0/00/Standard...
and a mètre étalon: https://upload.wikimedia.org/wikipedia/commons/2/22/Mètre-ét...
Edit: for completeness sake, a litre and décalitre (10L) étalon: https://portail.polytechnique.edu/musx/sites/pf_191/files/ac...