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Re: Migration from DTD to XSchema

From: Henry Luo <henryluo@vibrasoft.net>
Date: Fri, 23 Sep 2005 15:56:39 +0800
Message-ID: <4333B537.1080603@vibrasoft.net>
To: Pete Cordell <petexmldev@tech-know-ware.com>
CC: xmlschema-dev@w3.org

Hi, Pete

Thanks for the clarification.

My initial hope is that XML Schema can help me get rid of DTD complete. 
But it seems not always possible.
For example, if in my application, I'd like to make use of XHTML 
elements as part of my schema, the issues is how to handle those general 
XHTML entities?
If I don't include those XHTML entities in my schema, then probably I'll 
not always be able to cut and paste XHTML source code into my document.
If I do declare those XHTML entities in my reduced leftover DTD, 
definitely I cannot make it internal in each of my document, too bulky.
I'll have to put them in external DTD, then as we all know, 
non-validating parser might not be happy with that.

Won't our live be easier if XML includes those HTML entities by default?


Pete Cordell wrote:

> 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)">
> then
> <!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.
> HTH,
> Pete.
> -- 
> =============================================
> Pete Cordell
> Tech-Know-Ware Ltd
>                         for XML to C++ data binding visit
>                         http://www.tech-know-ware.com/lmx
>                         (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 07:59:38 UTC

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