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Re: Do you understand this?

From: Nic Ferrier
Subject: Re: Do you understand this?
Date: Sun, 06 Mar 2005 20:44:21 +0000

Richard Stallman <address@hidden> writes:

> Here's some text in man/url.texi that I don't understand.
>     HTTP allows specifying a list of MIME charsets which indicate your
>     preferred character set encodings, e.g.@: Latin-9 or Big5, and these
>     can be weighted.  This list is generated automatically from the list
>     of defined coding systems which have associated MIME types.  These are
>     sorted by coding priority.
> I am not sure what "these can be weighted" means, or what is
> generated from what.  Can someone please clarify this?

I don't know the specific code but I know about HTTP so here's an
explanation from that bias.

An HTTP request can specify the MIME types / charsets that are
accepted by the client. User agents can make the specification with
floating point values.

An example, from the HTTP spec (rfc2616) is:

       Accept: text/plain; q=0.5, text/html,
               text/x-dvi; q=0.8, text/x-c

If sent in an HTTP request for a resource /fred the above Accept
headers tells the server that the user will ideally accept /fred as an
HTML document or a text/x-c document. If those reprsentations are not
available then dvi is next preference. If none of those are available
then  plain text should be sent. If plain text is not acceptable then
the response would indicate a failure to find a representation that
satisfied the user's specifications.

This applies equally to charsets as well as type representations like
text/html and text/plain. You could, for exakple say this:

       Accept: text/html; charset=utf-8; q=0.5, 
               text/html; charset=iso-8859-1; q=0.3,

So when Emacs makes an HTTP request it should state the character sets
that Emacs could use to display a response in a buffer.

So the Accept header is generated automatically from the list of
available encodings.


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