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Re: A17: keep or drop entities?




% From: Bill Smith <bill.smith@Eng.Sun.COM>
%  
% I think the first version of XML should not support entities. Successive 
% versions should.
% 
% For those using SGML and entities, entity resolution and inclusion can be 
% performed on the server side. XML clients would expect "complete" documents
just 
% as today's HTML clients expect complete documents. This has proven an
acceptable 
% model for many documents and applications. Entity substitution on the client 

% side is not in great demand but extensible markup is.
% 
% Let's first include the features required to accomplish the leap from 
% one-size-fits-all markup to extensible markup. Once that is accomplished, we
can 
% add other useful features that we all know, love, and use.

I disagree. I think even the first version of XML should support entities,
including external text entities. If we want people to support XML (other than
the we-already-use-SGML crowd), we need to give them something that doesn't
exist in HTML, and entities are an important part of this. 

Any given user agent, whether for HTML or XML, must know whether the
object/file that is referenced in a document is to be shown inline, or not
shown. In the case of HTML, that is accomplished by having defined names for
elements. Thus an HTML UA knows that the SRC attribute on IMG points to a file
whose contents are to be shown inline, but the HREF attribute on A points to a
file whose contents are not to be shown. Instead, the contents of the A element
(which typically don't contain a file name or object reference of any sort) are
to be highlighted in some way. How is your typical XML UA to know what to do?
The information will have to be passed in some way. The standard &chap1; or
&leftarrow; tells an SGML UA to show the contents of the entity. 

How would the URL method cope with only inserting one paragraph out of a list
of paragraphs (or a database, for that matter)? We would have to come up with
an extension to the URL syntax to do so. One of the beauties of using external
entities is to have one document that contains all the boilerplate texts I need
for all my documents, and just change the name of the entity in the document
shown to get the appropriate boilerplate text showing up. This to me is a
reason for people to use XML. Some of the other reasons are rather nebulous to
the HTML users. And they are a large proportion of our potential XML users. If
we don't give these users enough first time around, they're not going to bother
waiting for the second attempt.

Lauren

--

Lauren Wood, SoftQuad, Inc