Understanding keyref constraints in XML Schema

Hello all.
I've been reading XML Schema Part 1 - Structures, and trying to understand the semantics of keys and keyrefs, and the rules by which documents are validated with respect to these constraints.. Specifically: given definitions of a key and a keyref, and a node in a document, I want to know which nodes are considered to be referencing it (according to the keyref). In the attached pdf file I've summarized the conclusions I've reached regarding keyref references in XML Schema. Since the standard (http://www.w3.org/TR/xmlschema-1/#cvc-identity-constraint) is not very clear, I don't know whether my observations are correct. I'd appreciate any comments regarding the attached document.

Thanks
Sharon Krisher