Some G words alter the state of the machine so that it changes from cutting straight lines to cutting arcs. Other G words cause the interpretation of numbers as millimeters rather than inches. While still others set or remove tool length or diameter offsets. Most of the G words tend to be related to motion or sets of motions. Table 4 lists the currently available g words.
| G0 | Rapid positioning |
| G1 | Linear interpolation |
| G2 | Circular/helical interpolation (clockwise) |
| G3 | Circular/helical interpolation (c-clockwise) |
| G4 | Dwell |
| G10 | Coordinate system origin setting |
| G17 | XY plane selection |
| G18 | XZ plane selection |
| G19 | YZ plane selection |
| G20 | Imperial system selection |
| G21 | Metric system selection |
| G40 | Cancel cutter diameter compensation |
| G41 | Start cutter diameter compensation left |
| G42 | Start cutter diameter compensation right |
| G43 | Tool length offset (plus) |
| G49 | Cancel tool length offset |
| G53 | Motion in machine coordinate system |
| G54 | Use preset work coordinate system 1 |
| G55 | Use preset work coordinate system 2 |
| G56 | Use preset work coordinate system 3 |
| G57 | Use preset work coordinate system 4 |
| G58 | Use preset work coordinate system 5 |
| G59 | Use preset work coordinate system 6 |
| G59.1 | Use preset work coordinate system 7 |
| G59.2 | Use preset work coordinate system 8 |
| G59.3 | Use preset work coordinate system 9 |
| G80 | Cancel motion mode (includes canned) |
| G81 | Drilling canned cycle |
| G82 | Drilling with dwell canned cycle |
| G83 | Chip-breaking drilling canned cycle |
| G84 | Right hand tapping canned cycle |
| G85 | Bring, no dwell, feed out canned cycle |
| G86 | Boring, spindle stop, rapid out canned |
| G87 | Back boring canned cycle |
| G88 | Boring, spindle stop, manual out canned |
| G89 | Boring, dwell, feed out canned cycle |
| G90 | Absolute distance mode |
| G91 | Incremental distance mode |
| G92 | Offset coordinate systems |
| G92.2 | Cancel offset coordinate systems |
| G93 | Inverse time feed mode |
| G94 | Feed per minute mode |
| G98 | Initial level return in canned cycles |
Table 4 G Code List
Tool diameter compensation (g40, g41, g42) and tool length compensation (g43, g49) are covered in a separate page. Canned milling cycles (g80 - g89, g98) are covered in their own page. Coordinate systems and how to use them is also covered in a separate page. (g10, G53 - G59.3, G92, G92.2)