Response to Simon St.L. on Entities v. XLL

Peter Murray-Rust peter at
Sun Nov 30 11:31:08 GMT 1997

At 21:29 30/11/97 +1100, Rick Jelliffe wrote:
>*  The SGML entity mechanism is based on having type information as part
>of the declaration of the entity, not in the entity reference and not in the
>entity itself.

I am very interested in automatic Typing of information components and
think that this will be a very active area for the XML community.

XML(SGML) entities (NOTATION) have traditionally used PUBLIC and FPIs
(Formal Public Identifier) for adding type information. This works if there
is a registry of FPIs for this purpose. Without it is not much use. My
impression - and I'm happy to be corrected - is that there are few useful
FPIs for Typing objects.

Using a SYSTEM Id is subject to the problem of permanence and uniqueness of

>*  The XLL mechanism (well, I should say the MIME mechanism really) is 
>based on the entity being self-identifying as to type (aided by 
>any additional attributes you like on the linking element).

Unfortunately, not all targets of XLL HREFs will be self-identifying. This
is true of local files and not-very-smart-servers.  It is therefore useful
for the author to be able to add MIME types to the target.
As yet, MIME is not part of the XLL mechanism. I wish it was, and keep
squeaking for it. If it isn't I suggest we use XDEV:MIME as a FUA
'frequently used attribute' in XML-LINKs.


Peter Murray-Rust, Director Virtual School of Molecular Sciences, domestic
net connection
VSMS, Virtual Hyperglossary

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