DISTANCE MODE (G90 AND G91)
Interpretation of the operating system code can be in one of two distance modes: absolute or incremental.
To go into absolute distance mode, program: G90.
In absolute distance mode, axis numbers (X, Y, Z, A) usually represent positions in terms of the currently active coordinate system. Any exceptions to that rule are described explicitly in this section.
To go into incremental distance mode, program: G91.
In incremental distance mode, axis numbers (X, Y, Z, A) usually represent increments from the current values of the numbers. I and J numbers always represent increments, regardless of the distance mode setting. K numbers represent increments.