Search behavior in webhelp output

Hi. I am fielding some questions about the search behavior in the
webhelp output. Is there an explanation of the behavior available
somewhere?

Specifically, I need to understand:

* How substrings are handled. Why does "locale" match "localeString"
but "crea" doesn't match "create"?

* Is there a way to search for strings that contain special characters
like periods. Can I search for "foo.bar" by escaping the period? Can I
remove the period from the list of special characters?

Thanks for your help. I have turned off stemming in case that matters.

Peter Desjardins