VXML-CCXML integration - Updating VoiceXML session variables

Hi,
 
I have a query regarding the managment of VoiceXML session variables in the
context of VXML-CCXML integration.
 
CCXML 1.0 Appendix D.3 mentions that VoiceXML Session variables are updated
whenever there is a update to the associated connection or conference.
 
What are the scenario in which this can happen? Can someone provide any
examples? Also, which are the exact VXML standard session variables that can
be updated by CCXML?  Are they only the VXML session variables defined in
CCXML or do they also include the VXML 2.0 standard session variables?
 
Also, from the VXML interpreter's perspective, does it need to verify the
dialog session state, when CCXML requests a session variable updation.
According to the specifications, VXML session variables and any applicable
sub-properties are read-only. Does this mean that they are read-only only
for the VXML application or script?
 
Thanks
Rajesh
 
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