Give the indexes of the crystallographic direction pointing towards the X-ray source. This direction may be a direction in the direct space if you activate the "Direct" button or a direction in the reciprocal space when activating the "Reciprocal" button.
Give the indexes of the crystallographic direction pointing towards the X-ray source, and thoses of the crystallographic direction along the vertical OZ axis. These directions may be directions in the direct space or in the reciprocal space, depending on the state of the "Direct" button or the "Reciprocal" button.