Wiki sucks terrible on so many surfaces.......... Its not definite source for sure.
Hence why it was only one of three cited links. 😉
As of OpenSearch:: it seems that its near deprecation, so its no worthy mentioning.........although the code itself is of pretty good quality and can be reused in something bigger...........
Mayhaps I am confused but did not Amazon "donate" it to OpenSearch.Org? 🤔
Although I personally would use nothing that - in any point of time - has been touched by Mozilla ( former / current ) employee ( s )
I presume you are referencing millisearch here? I did not look at its origins.