The IE encoding is a lot better. In order to support clients using it in requests, I have to be able to parse the filename, and the IE syntax is much, much easier to parse than the 2231-based syntax. Why not file a bug report against IE so that it works all the time?
The IE encoding is an ad-hoc solution. It doesn't work interoperably (it
depends on IE's locale), while RFC2231 works out of the box.
Why would anybody (except Microsoft) want to standardize the IE solution?
I also agree with the others that this isn't something that should be standardized in HTML, because it is not specific to HTML. I am implementing support for this (in both requests and responses) to my AtomPub implementations, for example. A seperate RFC for a *HTTP* Content-Disposition mechanism makes much more sense for use by non-HTML software. Make the IE syntax for the "filename" parameter the standard, and allow an additional "filename*" parameter for backwards-compatibility with UA's that implement the 2231 mechanism.
Well, Microsoft hasn't implemented RFC2231. What makes you think that
they would implement another RFC, when history tells that they just