A modular help system is one that is made of separate modules at "runtime", i.e. when the user is viewing it. Modular help systems are only possible in HTML Help (CHM) and the obsolete Winhelp (HLP) format.
A modular help system consist of a "master" module containing the main TOC, which must always be present, and one or more "child" modules, any of which may or may not be present.
Th: Disclaimer as master module ??