Perpendiculars. The forward and after perpendiculars shall be taken at the forward and after ends of the length (L). The forward perpendicular shall coincide with the foreside of the stem on the waterline on which the length is measured. <Chapter I, regulation 3>.
Source: IMO Resolution MSC.143(77), amendments to Annex B to the 1988 Load Lines Protocol, 5 June 2003, International Maritime Organization. Legislation