Question about `name="_charset_"`

[Kludex]

Hi again, 👋

Sorry to keep bothering, but I'm learning a bit more about multipart.

On the README, I see that you mention that _charset_ is discouraged.
I cannot find that in https://www.rfc-editor.org/rfc/rfc7578.html, is it from somewhere else?

[defnull]

Browsers follow https://html.spec.whatwg.org/multipage/form-control-infrastructure.html#multipart-form-data so field- and file-names should be encoded with utf8 by default for all modern web pages (plus partial percent encoding for exactly three special characters). All the legacy encoding schemes from the RFCs are no longer necessary, because segment headers are not required to be ASCII anymore. The algorithm to parse the Content-Disppsition headers also differs from that for normal HTTP headers. See #61 (not merged yet) for a details.

[defnull]

The readme is not completely honest here, RFC7578 does not discourage _charset_ but the W3C spec does. I should probably link that, too.

I'm also not completely against supporting _charset_ but I have not found any modern browser or library that does that yet, so I didn't bother. It would not be hard to implement, if needed.