Clarification text for issue #24

["Vambenepe, William N" <vbp@hp.com>]

Hi all,

I had an action item to propose clarification text for issue #24 as well
as explaining how to write a "Safe" Xpath statement. I just noticed that
Steve wrote such a clarification text for the benefit of the WSN TC so I
will borrow from this and just add the Xpath example:

<proposed addition>

If the value of the Xpath statement contains QNames, then the namespace
declarations that specify the mapping of the QName's prefix to an actual
namespace URI can be found amongst any namespace declaration in scope
for the element or attribute that contains the Xpath statement in its
value.  Note: Some XML processors may modify the namespace declarations.
Designers should be aware that such transforms exist and may render the
expression incoherent, as it is likely the change in namespace
declaration will not update a QName embedded within a string. 

The way to write a "safe" Xpath statement that is not subject to
breaking when XML processors modify namespace prefixes is to test
explicitly in the Xpath expression for local name and namespace, using
the Xpath functions local-name() and namespace-uri().

</proposed addition>

Regards,

William