http://www.bootslap.com/apps/articles/default.asp?blogid=0&view=post&articleid=Mechanical-Royalties-and-Licenses&link=1&fldKeywords=&fldAuthor=&fldTopic=0

This is really important because a lot of people don't know the difference between Royalties from Sales and Mechanical Royalties so i thought this might help you too.