How to improve a ERD

Question

This question is based on my plan at the thread.

My entity-relationship diagram is

alt text http://files.getdropbox.com/u/175564/sequence-diagram.png

Answer 1

This is my reply to rexem's answer.

I understand your answer as follows:

alt text http://files.getdropbox.com/u/175564/db-problem-2.png

and the second diagram as

alt text http://files.getdropbox.com/u/175564/db-problem-1.png

I left the xref table for the question-body because I may need to store the changes to my questions too in the future.