This determines when the tool axis vector is applied. The tool axis vector is the orientation of the tool shaft after the type of cut and lead angle are applied.
During XY
The tool orientation is applied during the first XY move at the beginning of the program.
At Top
The first XY move is completed. Then the tool orientation is applied.
During Z
The tool orientation is applied during the first Z axis move to the part. This is not recommended when there is no leadin move.
At Bottom
The orientation is applied after the Z axis move is made. The orientation is completed before the leadin move is started.