>>I still wonder how vfp knows what topic to call when you hit F1. At that moment it has your context ID of, say, 14. I can only guess that at that moment it searches all constants in memory for one that equals 14, then searches the current help file for a topic with the same name as one of the (possibly several) constants that equal 14. I am assuming that the context map file is not compiled into the .chm in any way, since its format varies with the programming environment.
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>No it's definitely compiled into the help file. The help file has an internal index that correlates topics with context ids. The #DEFINEs are just a byproduct that happen to be useful for your code to actually use the IDs by name rather than by number. You generally don't use these defines in most development environments - you'd use them in C, but not in VFP.
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>All the help engines are driven through APIs.There are API calls that perform the mapping of context ids to the actual HTML file inside the CHM that gives you your help topic.
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>This is one of the reasons I actually like HTML Help - it's very flexible in the way that you create help. Old HTML Help may have been faster but it was a bitch to create these files. With HTML it's very easy to create fancy help with minimum effort especially if you use a tool like HTML Help Builder, which is only an HTML front end that's template driven and programmable. This kind of demonstrates the power of HTML Help. I would have never been able to build this kind of tool for the old WinHelp format at least not without the help of some sophisticated third party controls...

I was confused partly because I mis-remembered what it said in the help for HHW.EXE and partly because I thought I had fixed my context-sensitivity by #INCLUDing the context map file in my vfp program. Actually it started working at that time because I simultaneously fixed something else, which is always perilous. I have also figured out that the .bas file that ForeHelp can make is not needed for context sensitivity by my Access 97 program, which apparently can only use a winhelp file.

Further confusing the issue is the description in the help for HHW.EXE of a text file for pop-up help topics which contains actual help text (not HTML, either) and which we evidently aren't using.