The drawings must be executed in black. Colour drawings can be submitted but will be scanned, printed and made available via file inspection in black and white only (see also A‑IX, 1.2 in respect of colour photographs). In respect of the content of priority documents issued by the EPO in such a case, see A‑XI, 5.2.
In all cases the thickness of the lines and strokes must take into account the scale, nature, execution and perfect legibility of the drawing and of the reproductions.
All lines must be drawn with the aid of drafting instruments save those for which no instrument exists, e.g. irregular diagrams and structures.