User requests help at field or control in dialog.
Application passes information about field/control to Mapping Table.
Mapping Table maps the field/control to Map Number.
Text file (.TXT), which is compiled into HTML Help file (CHM), contains Topic IDs and topic content in text-only format.
HTML Help identifies Map Number that matches field/control selected by user.
HTML Help translates Map Number into Topic ID using map files (.H) included in compiled .CHM file.
HTML Help looks up Topic ID in text-only topic file (.TXT) and displays appropriate What's This? Help topic in popup window.