Why does openTypeOS2VendorID fallback to `NONE`?

[lianghai]

ufo2ft/Lib/ufo2ft/fontInfoData.py

Line 378 in bd16616

openTypeOS2VendorID="NONE",

For reference, the spec says (cc @PeterConstable):

This field can also be left blank (set to null, or a tag comprised of four space characters).

By convention, only registered tags should be comprised of only uppercase letters (or space).

Fyi, the fallback used by Glyphs is UKWN, also strange (cc @schriftgestalt).

Neither NONE nor UKWN (nor ) is registered: https://learn.microsoft.com/en-us/typography/vendors/

[schriftgestalt]

I don’t remember why I pick UKWN. But it was probably what was commonly done back then.