A spatial reference point, through which the Centre-Line of the Beam
emitted by a SignalA visual display device which conveys instructions or provides prior warning of instructions regarding the driver’s authority to proceed. or Element should be directed, so as to achieve
satisfactory Visibility. The Alignment PointA spatial reference point, through which the Centre-Line of the Beam emitted by a Signal or Element should be directed, so as to achieve satisfactory Visibility... is specified in terms of its height
above rail level and its offset relative to the Left-Hand Rail, at a particular
distance from the SignalA visual display device which conveys instructions or provides prior warning of instructions regarding the driver’s authority to proceed..