Erik Veerman has written a nice article for the Solid Quality Mentors (who I also do training for) newsletter on attribute relationships and the RelationshipType property:
As he says on his blog, if you want to see more articles like this you can sign up for the Solid Quality newsletter here:
Hello again Chris! I think that there might be a wrong assumption in this whitepaper that you have mentioned above. MDX query performance does not care about rigid or flexible attribute relations, according to Mosha here:
http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=1254379&SiteID=1
I still do not know why I should use rigid attribute relations. It can save some aggregations in a measure group when you do an incremental update?
Have you any other information?