Everybody, who worked with Rational tools could think that there is nothing rational in them. And frustration mounts when you'll try to read the supplied documentation. The documentation is structured, but some pages are very shallow and others do not explain topics in undestandable language.
This article is very helpful. It actually shows how to structure design files, so the design will be understandable by anyone in the project.
At the end of page is a little gem: Software Architecture Document for the project, described in the article. Very very helpful!