New Issue: Clarification on Schema Variable Validation

New Issue: Clarification on Schema Variable Validation

Justification/Description: In Section 8.1, Variables, under Variable 
Validation, the <validate> activity and schema validation are described. 
However, the separation of these two concepts and the use of the latter 
needs editorial clarification.

Proposal: Clarify that validation of incoming and outgoing messages 
relates to schema validation. See attached .pdf that shows the change in 
bold green text and paragraph break suggested.