NDR: 4.4 Attributes in UBL

[Dave Scott <dms@haplos.com>]

In section 4.4 of the new draft of the UBL NDR, it says

"UBL, as a transactional based XML exchange format, has chosen to  
significantly restrict the use of attributes. This restriction is in  
keeping with the fact that attribute usage is relegated to  
supplementary components only."

The rule that corresponded to this text has been struck.  Does that  
mean that this restriction has been removed?

If the restriction is still meant to be included amongst the rules,  
I'm curious about the proffered justification for the rule.  I can  
think of some legitimate reasons for restricting the use of user- 
defined attributes.  However, I can't see how disallowing user- 
defined attributes has anything to do with UBL being a transactional  
based exchange format.

The best reason I can think of for disallowing user-defined  
attributes is that they potentially limit extensibility.  But one of  
the things you give up is the ability to use attributes for more  
efficient xml stream processing.

Does anyone have any insight into what the current justification is  
for the disallowing user-defined attributes?