[tei-council] Attributes in no namespace

Sun Dec 29 17:37:30 EST 2013

Hi all,

Here's a Christmas conundrum. This section of the Guidelines:

<http://www.tei-c.org/release/doc/tei-p5-doc/en/html/TD.html#TDeg>

contains an egXML whose purpose is to illustrate that it is possible to 
use the TEI @rend attribute to include styling information for example 
elements in the Examples namespace:

<egXML xmlns="http://www.tei-c.org/ns/Examples"
xmlns:tei="http://www.tei-c.org/ns/1.0">
<div>
     <head>A slide about <gi>egXML</gi></head>
     <list>
      <item><gi>egXML</gi>  can be used to give XML examples in the TEI
Examples namespace</item>
      <item>Attributes values for<att>valid</att>:
       <list tei:rend="collapsed">
       <item><val tei:rend="green">true</val>: intended to be fully
valid</item>
       <item><val tei:rend="amber">feasible</val>: valid if missing nodes
provided</item>
       <item><val tei:rend="red">false</val>: not intended to be 
valid</item>
       </list>
       </item>
       <item>The<att>rend</att>  attribute in the TEI namespace can be
used for recording how parts of the example was rendered.</item>
       </list>
</div>
</egXML>

Here, the "@tei:rend" attribute is intended to be an attribute in the 
TEI namespace, not the Examples namespace, and thus to be interpreted 
for rendering purposes rather than serialized as part of the example.

This strikes me as wrong. The @rend attribute we use in TEI is NOT in 
the TEI namespace; it's in the empty namespace. (Unprefixed attributes 
are not in the namespace of their parent elements.) In order for this to 
work, wouldn't we have to declare a special version of @rend which was 
explicitly in the TEI namespace, with the same semantics as the regular 
@rend, and use that? Because in terms of XML, these are two completely 
different attributes:

<p xmlns:tei="http://www.tei-c.org/ns/1.0"
    rend="blue"
    tei:rend="red">
	Blue or red?
</p>

The regular @rend is not in any namespace at all, according to the XML 
specification -- and incidentally also according to the RelaxNG 
specification, which I went and looked at; there, we're told that "A 
foreign attribute is an attribute with a name whose namespace URI is 
neither the empty string nor the RELAX NG namespace URI" 
(<http://relaxng.org/spec-20011203.html#full-syntax>) which means that 
our "TEI" attributes are defined with the empty string namespace, and if 
they were not, they would be "foreign" attributes).

So I contend that this @tei:rend attribute is not our own TEI @rend 
attribute, but a foreign attribute; and if we actually wanted to use the 
TEI attribute, we would have to do this:

<egXML xmlns="http://www.tei-c.org/ns/Examples"
xmlns:realTEI=""> ... <val realTEI:rend="red"...>...

But that in fact THIS cannot work either, because the @rend attribute 
used in the context of <egXML> elements in the Examples namespace is 
ALSO in the empty string namespace, and therefore they are no different 
from each other.

In other words, it is impossible to do what we set out to do in this 
example, according to the rules of XML.

Am I wrong?

Cheers,
Martin