Hi Terry,
This can be done simply in a macro I'm sure but I find writing anything outside of VS annoying. I written something similar to find G20 or G21 in Gcode. I used that plugin to edit quickly with all M codes listed for UCCNC up to M215. When loaded and enabled it will read Gcode when loading and if there's a M code not supported you will get a window with no match and with the M code not matched. I was having trouble making messagebox Topmost so make sure it's not buried behind UCCNC. Long day and after 1am and didn't have the patience.