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Re: CDATA vs. EMPTY

From: Bjoern Hoehrmann <derhoermi@gmx.net>
Date: Mon, 09 Jul 2001 03:50:47 +0200
To: peter@silmaril.ie
Cc: xml-dev@lists.xml.org, xml-editor@w3.org, w3c-ietf-xmldsig@w3.org
Message-ID: <pb0iktcgf7942j7t64j8rlnsvk00a0vrrf@4ax.com>
* Peter Flynn wrote:
>On Sun, 08 Jul 2001, Bjoern Hoehrmann wrote:
>> Hi,
>> 
>>    XML 1.0 SE says: "An element with no content is said to be empty".
>> Does the following fragment have any content?
>> 
>>   <elem><![CDATA[]]></elem>
>>
>> The Recommendation further reads: "The representation of an empty
>> element is either a start-tag immediately followed by an end-tag, or an
>> empty-element tag". This is true for the fragment in it's canonical
>> representation.

>In answer to your question: yes, your example does have content,
>but it does not have character data content. The direct
>equivalence of <elem/> with <elem></elem> only holds when the >
>of the start-tag is followed directly by the < of the end-tag.

I suggest to clarify XML 1.0 by making the word 'content' in the
definition of 'empty' a reference to '#NT-content'.

Btw.:

  Original Input            | Canonical representation
  --------------------------+-------------------------
  <elem />                  | <elem></elem>
  <elem></elem>             | <elem></elem>
  <elem><![CDATA[]]></elem> | <elem></elem>

Since in the original input the element is not empty, it is in the
canonical representation, I won't call that "logically equivalent",
maybe this should be listed in the "Limitations" section of XML C14N.

(x'posted to the relevant mailing lists)

Thanks for your comments.
-- 
Björn Höhrmann { mailto:bjoern@hoehrmann.de } http://www.bjoernsworld.de
am Badedeich 7 } Telefon: +49(0)4667/981028 { http://bjoern.hoehrmann.de
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Received on Sunday, 8 July 2001 21:51:27 GMT

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