The documentation set contains a comprehensive Master Index that is fully hot-linked to the books in the documentation set. When you click on an entry in the Master Index, the target book opens in its own window. In most cases, the browser will be positioned to the exact place in the text that is indicated by the master-index entry.
Here the user goes to the A section of the index, clicks on an entry that opens the Command and Shell User's Guide to the beginning of Chapter 5, and then clicks on an entry that opens the Programmer's Guide to information near the end of Chapter 11.