You need to enable Javascript or use a Javascript enabled browser to view the collapsible table of contents.
To enable JavaScript:
In Mozilla or Netscape 6, go to Edit, Preferences, Advanced, Scripts & Plugins and check the "Enable Javascript for Navigator" checkbox.
For Netscape 4.x, go to Edit, Preferences, Advanced and check "Enable Javascript."
For Internet Explorer go to Tools, Internet Options click on the Security tab then on the Internet icon and then Custom Level, look for a section marked Active Scripting and change it to Enable or Prompt.
For Opera 5, Select File,Preferences, click on the Plugin option, then make sure there is a check next to Enable JavaScript.