Macro line
From Macros Wiki
Macro lines are used to construct geometry. They are not drawn by GibbsCAM and are not the same as lines that you would normally create in GibbsCAM. You can define up to 100 macro lines (C1 to C100). If you need to see the line, then the CREATE_LINE command will create a GibbsCAM line using the center and radius of the given macro line. This is useful for debugging.