Add hover documentation for G-code instructions

[DavidHopkinsFbr]

You mentioned that you were looking for reference material you could use to add tooltip documentation for G-code instructions.

There's a lot of slightly different flavors of G-code with different supported features on different machines.

Here's the documentation for the supported G-code instructions of the Beckhoff TwinCAT CNC interpreter I'm using.

The Beckhoff TwinCAT CNC system is actually the ISG CNC kernel, integrated into a larger system. You can also download the ISG documentation and manuals directly from them. The programming manual contains full documentation of all the supported G-code. (It's also available in German if you prefer). It's basically the same as the Beckhoff TwinCAT CNC documentation linked above, but in a single PDF, instead of spread across a bunch of web pages.

Also, here is documentation for a G-code interpreter made by the US National Institute of Standards and Technology. The documentation includes detailed descriptions of exactly what the supported G-code instructions do.

There's also a simple list of codes and short names for Helman machines here.