Based on the three CHM (Microsoft Compiled HTML Help) files distributed with
the BUG mod (for Sid Meier's Civilization 4: Beyond the Sword 3.19) and
originally authored using WinCHM. Those files were last updated in
Oct 2008 (for BUG 3.5):
https://sourceforge.net/p/civ4bug/code/1450/

I hadn't, at first, been aware that the WinCHM template files are available through
the BUG SVN history, so I decompiled the CHM files in HTML Help Workshop 4.74 and
revised the resulting project and table-of-contents files manually. This setup now
works well enough for me, so I'm going to stick with it.

This repository also contains branches for the modified help files used by two
BUG-based mods.