Thanks for your question.
The primary purpose of the Centroid File is to program the Pick-n-Place (PNP) machine. However there is no standard format, and many PNP manufacturers have different definitions for both the Component Angle Origin, and rotation direction.
FAB 3000 default is at 3'O clock. This is where 0 degrees is defined. Some pick-n-place machines set their origins at 12'O clock, 6'O clock, etc. So if your Centroid file uses a different non-standard angle origin, you can allow FAB 3000 to correctly transform the angle during import.
Say a centroid file was generated for a PNP machine where 12'O clock was the angle origin. If a component is said to have 0 degrees rotation on that centroid file, then when importing all components will be off by 90 degrees - because FAB 3000 considers the origin to be a 3'O clock. By changing the "Centroid Import Setting - Angle Origin" value to 12'O clock - FAB 3000 can now adjust and add 90 degrees to all rotations in the file. Thus 0 degrees on that centroid file is really considered 90 degrees to FAB 3000.
Rotation (from Top side):
By default the rotation is counter-clockwise. Some PNP machines use rotation as clockwise.
Say a centroid file was generated for a PNP machine where rotation was given in clockwise direction. Thus if a component on that centroid file is rotated 90 degrees, it is really considered 270 degrees rotation to FAB 3000.