Thanks for the updates since the last version I reviewed (09) - The new version is somewhat easier to follow but I still find it a hard read - no so hard as to suggest holding the document for a rewrite but (imo) not as clear as it could be My last review objected to a SHOULD being used in section 5.3.1 and that was replaced by a MUST, which I think is a better choice but you have added a new SHOULD at the end of the same section and I have the same objection to the use of SHOULD in this case - it is my opinion that a MUST is better than a SHOULD unless you explain the exceptions to the SHOULD - so I think you need to change the text to use MUST or you need to add text that explains when one would not do what the text says to do