5.145. How should reference lines be shown? Reference lines (also referred to as leading lines), that is, lines between the reference signs (for example, reference numerals) and the details referred to, may be straight or curved and should be as short as possible. They must originate in the immediate proximity of the reference sign and extend to the feature indicated. Reference lines for certain reference signs may be omitted. Reference signs of this type, which are not connected to anything, will then indicate the surface or cross-section on which they are placed. In such cases the reference sign may be underlined to make it quite clear that the line has not been left out by mistake. Reference lines must be executed in the same way as other lines in the drawing (see paragraph 5.143).
5.146. Arrows may be used at the end of the reference lines provided that their meaning is clear. They may indicate a number of points:
(i) a freestanding arrow indicates the entire section towards which it points;
(ii) an arrow touching a line indicates the surface shown by the line looking along the direction of the arrow;
(iii) arrows may also be used in appropriate cases to show the direction of movement.
Date retrieved: 24 November 2017