Title: Namespace URI versioning Policy is not clear

Description: A review of the namespace URI versioning Policy revealed that it is not clear on 2 aspects. This is also illustrated in the email thread in [1]

1) It is not clear whether the third bullet is necessary given
that pattern facets are not used in WS-Policy specifications. 

It is also not very clear whether the second clause after the "or" is
really necessary either even if we were to retain that bullet. 

{Modifications to the pattern facet of a type definition for which the
value-space of the previous definition remains valid or for which the
value-space of the preponderance of instance would remain valid.} 
Which instances are we talking about? If we are referring to the
instances that were valid with the previous definition, I believe the
first clause already covers this intent. 

2) It is not clear what "cardinality of elements" refer to in the
fourth bullet:  

{Modifications to the cardinality of elements for which the value-space
of possible instance documents conformant to the previous revision of
the schema would still be valid with regards to the revised cardinality
rule.}

What is really targeted here, the cardinality of the value space or the occurance of the element (with minOccurs/maxOccurs)? The former is about the cardinality of the datatype of the element and should not be referred to the element cardinality... 

If the intention of the last bullet is speculated, it appears that the bullet is not talking about value spaces here but perhaps trying to indicate
that the occurance of the elements in the new schema should be covering
the occurances of the instances of the same element in the old schema
(ie. 0,n -> 0, n+1) 


Justification:

WS-Policy is the first specification that clearly states a namespace URI versioning policy. Hence, it will set the expectation of how namespaces may change with respect to compatibility rules in other specifications in the future.  Therefore, we carry the responsibility to state very clear rules so that there is no misinterpretation to the policy as this policy will set the precedence in the industry.  

Target: Both Framework and Attachment specifications

Proposal: 

(1) There are two options 
    (a) Remove the bullet 
    (b) Just remove bag "preponderence" clause? The instances that
were valid with respect to the previous definition will remain valid
anyway. 

(2) Clarify whether it is the cardinality of the elements rather than value space. This is a TBD item pending on the intent of the wg. 


The thread can be found in [1] 

[1] http://lists.w3.org/Archives/Public/public-ws-policy/2006Aug/0091.html