Barry,
Short answer: I don’t know. I run LinuxCNC.
Long answer: I would assume the XML profile would include the configuration info for my board, step and direction pins and such.
XML files are human-readable, and are able to be edited using any NotePad-like text editor (I would avoid using WordPad or WORD unless you know your way around saving a text-only file).
Care should always be exercised when manually editing an XML file. A missing backslash can really ruin your day.
Your best bet is to review the Mach3 documentation. They’ve really done a great job.
BrianV