Thanks Tweaky!
Um...not sure what you mean by "online" - I run it from Thonny on my PC (or could be Mac / R-Pi or any Linux machine), which is a Python IDE. You give it a filename (when it asks) and it writes the code into a file with that name. I think it might be possible, if you are running it on the same machine as Mach 3/4, to insert the full file path to the folder where Mach3/4 keeps its G-code, otherwise it just writes the file into the folder where the code is. I run Mach 3 on an old XP machine and getting Python on XP (especially without an Internet connection) seems to be hard! So I tend to generate the code on my office PC and save it on to a USB stick and sneakernet down to the workshop.
If only Mach 4 had used Python for macros and wizards instead of Lua...
John.