The Depth is the total depth that  it is going to cut and the Finish depth is the amount that is going to be left for a finish pass.

I think that is how it works from reading the code this morning 

BRIAN, you posted the download above BUT ! this newbee don't know yet what to do with it or where to put it. I just haven't run into this yet and figured I'd ask instead of experimenting. Thanks

If you have Mach3 installed to the default location you place it in C:\Mach3\Addons\Surfacing with tool down in X

Hood

Thanks for all the info guys. I have finally got it 

As an aside : Let me ask about the type of cutter shown in the wizard. I have a cheap (Asian) one that came with my Asian mill.
It has three inserts and I notice that they are not all at the same depth. Is this normal (each insert taking a progressively deeper bite) or are they supposed to be all at the same depth?

I would say they are supposed to be all the same depth.
Hood