Re: Comments on MIME/SGML

"Daniel W. Connolly" <connolly@hal.com>
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Date: Fri, 25 Feb 1994 12:23:37 --100
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From: "Daniel W. Connolly" <connolly@hal.com>
To: Multiple recipients of list <www-talk@www0.cern.ch>
Subject: Re: Comments on MIME/SGML 
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In message <9402211509.AA01936@ptpc00.cern.ch>, Tim Berners-Lee writes:
>Dan,
>
>>    1. We make the following correspondence between the terms of the SGML
>>    standard and the MIME RFC:
>    
>
>...
>>        SGML SYSTEM identifier => MIME Content-ID
>
>	I proposed in an earlier note that the SGML SYSTEM identifier
>	should be a URI and that a special form of URI (cid:) should
>	be used to specify a content identifier within a MIME
>	multipart message.
>	
>
>	SGM SYSTEM identifier  => URI
>	
>	
>	This allows SGML to reference anything in the universal
>	syntax, inclusing now URLs and later URNs, and
>	other parts of a MIME object using the cid: form.
>	I think this is important, as external references
>	are important too, and one will need to mix them.

So far we've only been talking about MIME and SGML. Neither MIME
tools nor SGML tools currently grok URI's. I see no reason to
introduce that much new technology just to allow a MIME message to
hold multiple SGML entities.

Besides: MIME already specifies a way to reference bodies outside
the message: message/external-body. e.g.:

	Content-Type: multipart/x-sgml; boundary="cut-here";
			document=id1

	--cut-here
	Content-ID: id1
	Content-Type: text/x-sgml

	<!DOCTYPE HTML [
	<!ENTITY % htmldtd SYSTEM "id2">
	&htmldtd;
	]>
	<html>...</html>

	--cut-here
	Content-ID: id2
	Content-Type: message/external-body;
		access-type="anon-ftp";
		site="info.cern.ch";
		directory="pub/www/doc";
		name="HTML.dtd"

	Content-Type: text/x-sgml;

	
	--cut-here--

Dan