Certain languages can't be matched correctly by the Regular Expression EXT_VALUE_REGEXP like en-US or zh_cn

[wally-li]

No description provided.

[dougwilson]

Hello, and very sorry about that! I tried to make the regular expression match the grammar as defined in RFC 5987. Looking at the spec, I don't believe either of those would be valid. Can you please point out where in the spec those would be valid values?

[wally-li]

I'm so sorry, they seem to be out of this spec.I didn't know this The Language Tag Spec before.But why can the chrome browser can parse the attachment's name correctly when I access the dowload url by address bar even though the content-disposition field contains invalid information for languge?

[wally-li]

I read the spec in https://datatracker.ietf.org/doc/html/rfc5646#section-2.1. the spec about the language region is 2ALPHA or 3DIGIT.In other words,en-US meets the language tag specification.But for EXT_VALUE_REGEXP, /-A-Za-z]{3}){0,3}/ states '-' must be followed by three characters.