Information types control which books and pages a user can access from the Contents tab in the HTML Help viewer. They are an optional feature that you can use in Microsoft HTML Help projects only.
You first define categories and add information types to them. Then assign topics (pages or books) to the information types. From the Contents tab in the HTML Help viewer, users can customize books and pages that appear in the table of contents. If you do not assign an information type to a topic, the topic appears in the HTML Help viewer regardless of user customization.
A category is a way to group information types, such as job description or skill level. You can create up to 10 categories and 32 information types.
Information types fall into two categories:
All information types from a category are available to users.
Restricts users so they can select only one information type from a category. For example, you can assign Exclusive classifications by skill level, so that users can access only the Help topics that pertain to their skill level.
With the current version of Microsoft HTML Help, it is not possible to filter Index and Search tabs to support information types. Users cannot access a topic from the HTML Help index that is not in the information types that they select.
For a detailed explanation of information types, seeby Rob Houser.