Output Preset / General /Start Page

I'm confused. You say you know but you asked the question. Perhaps you hadn't connected the RoboHelp start page with being the same as a web site start page?

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My site www.grainge.org includes many free Authoring and RoboHelp resources that may be of help.

I know.  For another site, I had IT specify a set of acceptable "home" pages for the browsers to use. 

Try opening the help without one. 🙂 Web sites all have a start page, typically index.htm. They are what opens the site or in this case the help.

When you open a web site such as www.adobe.com the reason you don't type index.htm is because browsers allow certain filenames as defaults. home.htm and default.htm are two others you don't have to enter.

In RoboHelp as with any website, you can call that page whatever you want. However, you then have to include it in the address bar or the link.

________________________________________________________
My site www.grainge.org includes many free Authoring and RoboHelp resources that may be of help.