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You are misunderstanding the way RoboHelp works. The TOC is similar to a simple web page that simply contains links to other pages. Just as you might have many pages in a web site that aren't referenced by a front end page, the TOC works similarly.
If your goal is to include only content found in the TOC, you need to investigate using Conditional Build Tags and Conditional Build Expressions that will be used to exclude content from the build.
Helpful and Handy Links
Ah, fair enough! Thanks!