there is a lot of information about this topic, but much of what I found concerns old Windows versions and is sometimes contradictory.
The question is: how do I link the master project to the subprojects, allowing the application to call the master with a map ID that displays a page in the subproject? Naturally the TOC should sync to give the appearance of a coherent help system. This should work under Windows Vista (and XP of course) with Microsoft HTML output.
Perhaps you can you recomment a souce for up-to-date info about this? Please excuse if I have overlooked a previous discussion, I did a search but did not find a match. The forum search engine is a bit tricky too.
The information on the Helpware site is still valid, even if it's been around for a long time now.
To my knowledge, these are the only published ways to channel a context integer through the master Help file to a slave.
There is an alternative and simpler solution that involves the use of the HTML Help API command HH_DISPLAY_TOPIC, which passes a topic file name rather than a context integer to the master Help file. I've described this here:
many thanks for your help. Your links are exactly the info that I hoped to find.