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Appling inheritance rule to xml:base, was Re: FINAL minutes for the XML Core WG f2f meeting...

From: John Boyer <boyerj@ca.ibm.com>
Date: Sun, 5 Mar 2006 17:47:54 -0800
To: "Grosso, Paul" <pgrosso@ptc.com>
Cc: public-xml-core-wg@w3.org, public-xml-core-wg-request@w3.org
Message-ID: <OF8194FF62.14677AE7-ON88257129.00082B59-88257129.0009E18D@ca.ibm.com>
Hi Paul,

After having a little time to digest the new information about xml:base 
and inheritance,
I realized that the argument presented has nothing to do with whether 
xml:base should
be inherited into the serialization by orphaned element nodes when it does 
not appear 
on those orphaned nodes.

Because not everyone reading this list was at the meeting, here is a 
review of the
issue:

<a xml:base="http://example.org">
   <b xml:base="test">
       <c xml:base="test"/>
   </b>
</a>

Now, write an Xpath filter that keeps a, omits b (and its attributes) and 
keeps c.
Resulting serialization is

<a xml:base="http://example.org">
       <c xml:base="test"/>
</a>

So, as a result of the omission filtering, c has lost critical context.

However, this is just an instance of the *usual* type of critical 
information that
can get lost when people are careless with omission filters.

When you look closer at this example, you can see that it has nothing to 
do with 
the attribute inheritance rule because c *has* an expressed xml:base.  In 
other 
words, the example above only shows the insufficiency of the xml:base 
attribute
inheritance rule, not that the rule is unnecessary. 

The C14N rule for inheriting xml:base was added in consultation with the 
xml:base
team, I believe, based on the belief that, when it did actually occur, it 
would be to
the benefit of the user.  To put a real example on it, it means that using 
the same
filter to omit b and its attributes, the following:

<a xml:base="http://example.org">
   <b xml:base="test">
       <c/>
   </b>
</a>

usefully serializes as

<a xml:base="http://example.org">
       <c xml:base="test"/>
</a>

In conclusion, the new C14N should apply the inheritance rule to xml:base, 
not just
xml:lang and xml:space.  This will avoid breaking existing systems that 
have relied
on this behavior since xml:base became a recommendation.

John M. Boyer, Ph.D.
Senior Product Architect/Research Scientist
Co-Chair, W3C XForms Working Group
Workplace, Portal and Collaboration Software
IBM Victoria Software Lab
E-Mail: boyerj@ca.ibm.com  http://www.ibm.com/software/

Blog: http://www.ibm.com/developerworks/blogs/boyer





"Grosso, Paul" <pgrosso@ptc.com> 
Sent by: public-xml-core-wg-request@w3.org
03/03/2006 03:18 AM

To
<public-xml-core-wg@w3.org>
cc

Subject
FINAL  minutes for the XML Core WG f2f meeting...







 
are at

http://www.w3.org/XML/Group/2006/02/xml-f2f-20060302-minutes.htm

We finished by (our) midday, so short of corrections,
those should be the final minutes now.

paul
Received on Monday, 6 March 2006 01:48:03 GMT

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