This was an important study in the history of computer security. It kicked off a lot of work on security, although a lot of it didn't pan out. Among other things, this study led to the Orange book. A good historical overview of what happened is in "The Birth and Death of the Orange Book" by Stephen Lipner; he was one of the people who wrote this cited study: https://www.stevelipner.org/links/resources/The%20Birth%20an...

Much of the results were sadly a cautionary tale. The government wrote down a set of its perceived requirements for handling classified material, but then the entire computing environment changed in a way they hadn't anticipated.