11.—(1) For the purposes of this Regulation—
"minor road" means a road at a road junction on which road is placed the sign shown in diagram 601 or 602;
"major road" means the road at a road junction into which road emerges vehicular traffic from a minor road.
(2) The requirements conveyed by the sign shown in diagram 601 shall be that
(a) every vehicle shall before entering the major road stop at the transverse lines shown in diagram 1002 or, if they are not for the time being visible, at the major road; and
(b) no vehicle shall proceed past such one of the said transverse lines as is nearest to the major road into that road, or if those lines are not for the time being visible shall enter into the major road, in such a manner or at such a time as is likely to cause danger to the driver of any other vehicle on the major road or as to necessitate the driver of any such other vehicle to change its speed or course in order to avoid an accident with the first mentioned vehicle.
(3) The requirement conveyed by the sign shown in diagram 602 shall be that no vehicle shall proceed past such one of the transverse lines shown in diagram 1003 as is nearest to the major road into that road, or if those lines are not for the time being visible shall enter into the major road, in such a manner or at such a time as is likely to cause danger to the driver of any other vehicle on the major road or as to necessitate the driver of any such other vehicle to change its speed or course in order to avoid an accident with the first mentioned vehicle.
12.—(1) Where the circumstances so require, the indications given by the signs shown in the diagrams in Schedule 1 shall or may be varied as hereinafter provided in this paragraph
(a) any indication given by such a sign may be varied in the respect (if any) in which it is shown below the diagram relating to that sign that the indication may be varied;
(b) in the signs shown in diagrams 502, 503, 523, 524, 527, 530, 531, 534, 535, 547, 570 to 573, 623, 626, 628 to 631, 746, 826, 840 to 843, 914, 915 and 916 (second distance only) the numerals shall be varied to accord with the circumstances;
(c) in the signs shown in diagrams 618, 639 to 641, 807 and 819 the legend shall be varied to accord with the prohibition or restriction imposed in relation to vehicular traffic;
(d) in the signs shown in diagrams 515, 553, 568, 569, 573, 606 (through 180° above horizontal), 639, 640, 644,810,840 to 842 and 912 the direction of any arrow or chevron shown therein shall be varied to accord with the circumstances, and in the signs shown in diagrams 639 and 640 the arrows may be omitted and in the signs shown in diagrams 534, 535, 641 and 746 an arrow pointing in the appropriate direction left or right may be included;
(e) in the signs shown in diagrams 570, 573, 746 and 840 to 842 any distance shown therein may be expressed in yards or miles as is appropriate and in the signs shown in diagrams 518, 519, 534, 535 and 563 an indication of distance may be expressed as is appropriate;
(f) in the signs shown in diagrams 713, 724, 728, 732 to 741, 903 and 904 the direction in which they point shall be reversed;
