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Re: Migration from DTD to XSchema

From: Pete Cordell <petexmldev@tech-know-ware.com>
Date: Fri, 23 Sep 2005 08:17:10 +0100
Message-ID: <003201c5c00e$d512a050$a300a8c0@RW>
To: "Henry Luo" <henryluo@vibrasoft.net>, <xmlschema-dev@w3.org>

Hi Henry,

The answer is yes and no!

There is no equivalent to general entities (&foo;), but that can be left as 
part of an internal DTD in an XML instance document.  (Unless you have a 
controlled environment general entities in external DTDs are best avoided in 
case your instance ends up at a non-validating parser.)  So this use of 
entities is not really in scope for schema.

One use for parameter entities (%foo;) is the defininition of common groups 
of element references, e.g.:

<!ENTITY foo % "(bar | la | tee)">


<!ELEMENT MyElement ( a | b | %foo; )>

Schema supports this use with the xs:group construct.

I can't think of other uses of parameter entities are supported.

Conditional inclusion of DTD sections is not supported either.


Pete Cordell
Tech-Know-Ware Ltd
                         for XML to C++ data binding visit
                         (or http://www.xml2cpp.com)

----- Original Message ----- 
From: "Henry Luo" <henryluo@vibrasoft.net>
To: <xmlschema-dev@w3.org>
Sent: Thursday, September 22, 2005 7:40 PM
Subject: Migration from DTD to XSchema

> Hi, Everyone
> I'm new to this list. I'm not sure whether the following question has been 
> asked.
> I'm planning to migrate out from DTD to XML Schema on some of our XML 
> files.
> However, I cannot find the equivalent of the DTD Entity declaration in XML 
> Schema, or is there?
> So does it mean that I can only convert the element and attribute schema 
> from DTD to XML Schema, and still have to leave entity declarations in 
> DTD?
> Henry
Received on Friday, 23 September 2005 07:17:23 UTC

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