questions about exc-c14n

Hello, List!

I am working on C14N and Exc-C14N standards implementation 
based on gnome-xml library and I have few questions about ext-c14n. 
It'll be great if someone can help me with it.

Thank you in advance,

Aleksey.

Questions about Exc-C14N:
-------------------------------------------------------------
1) Do we need to exclude default "xml" namespace "xml"
with href="http://www.w3.org/XML/1998/namespace" when 
a node has an attribute in this namespace (for example, 
"xml:space") as it is done in C14N? I suspect that the answer
is "yes" but want to confirm it.
2) The same as above but the default namespace is in the 
InclusiveNamespaces PrefixList?
3) From the documentation it is not clear should the 
namespace utilized by an "invisible" attribute (i.e.
the attribute not in the XPath subset). I guess the answer
is "no" but it'll be better to make it more clear.
4) one of exc-c14n tests I found in this mailing lists
(http://lists.w3.org/Archives/Public/w3c-ietf-xmldsig/2002JanMar/0097.html)
processes attached document test.xml with following 
results (spaces and line breaks are corrupted):
>EXC-C14N ON e6 SUBSET
>policy: xmlsec-python> test_c14n.py -e -i eg3.xml -x 
> '(//. | //@* | //namespace::*)[ancestor-or-self::e6]'
><e6 test="../baz">
>	<e7>
>		<e8 xmlns:a="http://www.w3.org" a:foo="bar">
> 			<e9 attr="default"></e9>
>		</e8>
>	</e7>
></e6>
>aaddbe1fdb6122ad46af56e038bd721b

However, I am not sure I understand why there is no namespace definition 
xmlns="http://www.ietf.org" in <e7> node. AFAIK, this node utilizes
this attribute itself since it has following definition in original 
document: 
	<e7 xmlns="http://www.ietf.org">  	
and according to specification:
 "A similar definition applies for an element E in a document subset 
 that visibly utilizes the default namespace declaration, which occurs 
 if E has no namespace prefix."
Will you clarify this, please?