Re: Comments on MIME/SGML

Daniel W. Connolly (
Fri, 25 Feb 1994 12:23:37 --100

In message <>, Tim Berners-Lee writes:
>> 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";

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

<!ENTITY % htmldtd SYSTEM "id2">

Content-ID: id2
Content-Type: message/external-body;

Content-Type: text/x-sgml;