I should have mentioned that, as I was aware of it. My layer of BS was getting pretty thick, so I tried to pare it down to giving a concept instead of instructions.
The lap dulcimer is strictly a one-scale diatonic instrument in its basic form. You can change which scale by retuning. Adding the 6-1/2 fret lets you "sort of" have two major scales on the same instrument. Adding the rarer 1-1/2 fret gives three (sort of).
And guitar tab should be able to show hammer-on and pull-off notations, and probably bends, for completeness.(?)