Here's my suggestion, but before applying, I'd like to get a second opinion by@ddbeck, who might have a better idea.

FWIW, this sounds good to me.

The corresponding docs have just been merged, so I'd like to expedite adding this data.

I like your suggestion, so for now I'm going to make this update in the places it appears. If we want to improve it further, I am happy to do so in a follow-up PR.

This text is fine, but see my other comment on the whole structure of this feature:#28275 (comment)

@Elchi3 What do you think about this behavioral subfeature?

You didn't ask me so FWIW, I'm -1 on this as a feature or at least one that is"standard_track": true. The linked "spec" says:

This section serves as a descriptive record of theUser-Agent patterns found in the so-called major web browsers

If it's descriptive, then it's merely documentation that does notspecify anything. The spec doesn't actually say what the vendors must or should do, just what they have done as convention. I think this is comparable to linking to an MDN page in aspec_url.

I think this would be better as a note that says exactly what's being reduced. Something along the lines of:

From version 110, the reported browser version number is always in the pattern ofX.0.0.0 whereX is the major version number.

Your logic here sounds reasonable, but downgrading this to a note troubles me a bit. I am documenting user-agent reduction and what it means to the values reported by theUser-Agent HTTP header (and associated API features). In a couple of places,like here in the user-agent reduction guide I link to the browser compat table to let people know which browsers support this.

I worry that if it is just a note, it'll be fairly easy to miss the note.

Yes, I acknowledge this concern and I agree that is a bit obscure in a note. That said, maybe a change to the docs might help? My suggestion for the docs would be to be somewhat more aggressive in saying that thecontent of a UA string is not actually standardized (even if the string's format is) and, theoretically, could change at any time. The browser tables might tell you how and when UA strings have changed, but I would hate to suggest to a developer that they could or shouldrely on that information.

Fair point. Could we do both?

I'd still like UA reduction to be called out in the compat tables (and let's face it, we'll need to add another data point if a browser decides to do a U-turn, whether the info is contained in notes or separate data points).

But I also see the value in updating the doc that the data point links to, to make it clearer that the UA string content is still not standardized.

If that means we can putstandard_track: true, then I think it is a good idea.

It would still be good to update the docs, as previously discussed.

I did not think editing the spec would be an option. That would be ideal!

OK, so if@miketaylr can make that change to the spec, I don't think there is anything more for me to do here?

The relevant issue to follow iswhatwg/compat#272 - I will be at TPAC next week and will aim to make edits to resolve. Feel free to merge this on faith, or wait. :)

If possible, it would be nice if the spec update could explicitly introduce the term "User-Agent reduction" with a specific identifier to which BCD could link instead of the more generalThe User-Agent String section.