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Re: [xml-dev] Text/xml with omitted charset parameter

Among other things, this means that the same document may be interpreted with a different encoding when read from HTTP than when read from the local file system. YUCK! This is a major interoperability problem. 

Perhaps worse yet, since the default for text/xml is us-ascii and not utf-8, this means that serving an XML document using any non-ASCII characters over HTTP requires the author to set the charset parameter of the MIME media type. This is non-trivial in most environments and impossible in many. According to RFC 3023, "US-ASCII was chosen, since it is the intersection of UTF-8 and ISO-8859-1 and since it is already used by MIME." However, this really strikes me as insufficient justification given the major practical problems it presents for non-ASCII documents. Is there any chance of superseding this RFC with one that specifies UTF-8? This still isn't perfect, but it at least allows full use of Unicode. 

Interestingly, application/xml does not have this problem, at least not all of it. In the absence of an explicit charset parameter, then application/xml falls back to the normal heuristics for guessing the encoding of an XML document (e.g. byte order mark, encoding declaration, etc.) There's still a problem if the MIME charset disagrees with the document internal information, but in practice this isn't nearly as big a problem. Maybe that's what should be done with text/xml as well? It certainly seems to be what Mozilla is already doing. 

In the meantime, I think I'm going to start recommending the use of application/xml and deprecating the use of text/xml. 

| Elliotte Rusty Harold | elharo@metalab.unc.edu | Writer/Programmer |
|          The XML Bible, 2nd Edition (Hungry Minds, 2001)           |
|              http://www.ibiblio.org/xml/books/bible2/              |
|   http://www.amazon.com/exec/obidos/ISBN=0764547607/cafeaulaitA/   |
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