@TalbotG I am indeed still active in WPT, but to get the attention of a wider group of people maintaining it, you can mention @web-platform-tests/wpt-core-team.

It looks like the problem is that there are no lints for any flags at all, valid or invalid. I've renamed the issue to reflect this.

Is the "svg" flag useful for you to add to tests? If so I'd say you can simply keep doing so, and perhaps add a description of when it's useful in http://web-platform-tests.org/writing-tests/css-metadata.html#requirement-flags.

Is the "svg" flag useful for you to add to tests?

I used to add the "svg" flag for tests that were using an svg object. This was the normal procedure before.

"svg | Requires support for vector graphics (SVG)"
https://wiki.csswg.org/test/format#requirement-flags

There are some web-capable softwares that want to be and/or strive to become (now or in the future) W3C-web-standards-compliant (at least regarding CSS) which may not have support for SVG objects. Therefore why the usage of the svg flag arised. Let's say they import, set up and run the entire CSS repository: they do not want to run tests that have svg objects because their software can not handle those. Then such flag would be useful to them.

I would say that flags' items are useful for filtering or screening tests (regarding a specific criteria) for those who import, create and run repositories of tests.

to get the attention of a wider group of people maintaining it, you can mention @web-platform-tests/wpt-core-team

I wrote down this (useful!) information. Thank you Philip

If this is a flag that the css folks feel is useful, I think that documenting it (the file is docs/writing-tests/css-metadata.md, PRs are welcome ;)) is a good idea.

Additionally, a lint for css/ against deprecated flags seems reasonable too.

I'm not clear what other lints would be both practical and useful. Meta tags are author-defined, and some authors may with to use them with different names or contents and so I'm not sure we should impose there (even for cases like the flag typos @foolip found). Open to ideas though!

If this is a flag that the css folks feel is useful,

I do not know.
I have checked the documentation of some web-aware and CSS-capable user agents like Prince 13 and Antenna House 7 and to my surprise, they appear to support (at least partially) SVG objects.
Some other newer web-aware and CSS-capable user agents (eg gngr ) do not support SVG objects.

a lint for css/ against deprecated flags seems reasonable too.

I am for a lint for css/ checking against deprecated flags and also unknown or invalid flags. Eg #23264
"border-radius" and "box-shadow" are not - and never were - valid flags.

Some other newer web-aware and CSS-capable user agents (eg gngr ) do not support SVG objects.

With more research, even gngr is looking, planning to support svg objects:
Support for SVG images in gngr