A new casebook on the ISAF website with the changes from the supplement RRS 2010. You can go to the ISAF download page to save your copy.
I did a search on 18.2(c) and did read a couple of pages, but haven't had time to go through all cases to find the changes. If you do, don't hesitate to tell us in a comment.
To summarize: rule changes have been made in rule 18.2(c) and two definitions: Obstruction & Party.