I’m quite sure. The compatibility tables are meant to give developers a quick reference for what is currently supported and a bit more historical context when needed.
- Items without version numbers have either always or never been supported by that browser.
- A check mark indicates it has always been supported.
- An X indicates it has never been supported.
- An item that only has one version number (
78) indicates that support was added in that version.
- An item with two version numbers separated by a dash (
57 – 68) indicates support was added in first value and removed in the second.
If you’d like to dig deeper, I’d suggest starting with the mdn/browser-compat-data repo. Specifically, check out the webextensions/api/downloads.json file and reference the
version_last sections of the schema docs. It might also be worth noting that this is where the version range is output in the compatibility table.
Per your interpretation, I would expect a green 48-68, followed by a red x 69
Unfortunately, displaying that much information in the compatibility table would make it more difficult for readers to quickly and easily assess what they can/can’t use right now.
download attribute or the web platform’s File System Access API.