A spiral path does not have a clear transition from the first track to the second track, while the circular path will not have any transition to the second track unless there is a clear transition. This is the difference between layerless and layerwise powder bed fusion. In layerwise (circular track), there comes a point when the index moves up from the first track to the second track; this point comes after completion of the first track. This index shows a discontinuity in fabrication, which makes it layerwise. Without this discontinuity, the ongoing fabrication will not resume. In layerless (spiral track), there never comes a point for the index to move up from the first track to the second track, but the transition takes place—it means the index starts to move up before the end of the first track and continues moving up after the end of the first track. This upward movement of the index does not consume a point in the space but consumes a line. This line consists of the end section of the first track and the start section of the second track.