CSS

I've analyzed the browsers.css-data.json file and found 5 items whose browsers field contains a value that doesn't match the "(E|FFA|FF|SM|S|CA|C|IE|O)([\\d|\\.]+)?" pattern specified in the https://github.com/microsoft/vscode-css-languageservice/blob/main/docs/customData.schema.json#L86.

Here they are:

overflow-anchor: 'Spreview'
-moz-background-clip: 'FF1-3.6'
-ms-filter: 'IE8-9'
-ms-transform: 'IE9-9'
-ms-transform-origin: 'IE9-9'

BTW, why are we looking for the | character in the [\d|\.] part? 🤔 There is no single value that contains this character.

But there's a - character. Is this a valid character?

If it's valid, what does it mean then? That the feature was supported e.g. from version 1 to version 3.6, and then was kicked out? But then what does a value like 'IE9-9' mean? That the feature was only supported in version 9?

Then it makes sense to replace the | character to - in the pattern?

If it's not valid, then these values should be fixed in the browsers.css-data.json file.

The value 'Spreview' looks invalid. Correct me if I'm wrong. What does it mean? That the feature is only available in the experimental build of Safari, regardless of version?

HTML

I've also analyzed the browsers.html-data.json file and found 9 items whose baseline_low_date or baseline_high_date fields contain a value that doesn't match the "^\\d{4}-\\d{2}-\\d{2}$" pattern specified in the https://github.com/microsoft/vscode-html-languageservice/blob/main/docs/customData.schema.json#L189 and https://github.com/microsoft/vscode-html-languageservice/blob/main/docs/customData.schema.json#L195.

They have values like ≤2020-07-28 instead of just 2020-07-28 and can be easily found in any text editor by the ≤ character.

I'm assuming these are invalid values.