Comment:

The four major sections of the IG are only accessible from the Home Page and the Table of Contents. There is also a tab for Profiles and Extensions and a section for Profiles and Extensions that take the user to two different sections of the guide. Breaking these out into their own tabs on the navigation bar or including them on existing tabs (e.g. including the Introduction on the Home page) would make the guide easier to navigate and more understandable by the end-user.

Summary:

Include the sections in the navigation bar