(3) The sheets shall contain frames around the usable or used surface,
and the minimum margins shall be as follows—
(a) top—2.5 cm.;
(b) left side—2.5 cm.;
(c) right side—1.5 cm.; and
(d) bottom—1.0 cm.
(4) Drawings shall be executed as follows—
(a) without colouring in durable, black sufficiently dense and dark,
uniformly thick and well-defined lines and strokes to permit
satisfactory reproduction;
(b) cross sections shall be indicated by hatching which does not
impede the clear reading of the reference signs and leading lines;
(c) the scale of the drawings and the distinctness of their graphical
execution shall be such that a photographic reproduction with a
linear reduction in size to two-thirds would enable all details to
be distinguished without difficulty, and where the scale is given
on a drawing it shall be represented graphically;
(d) all numbers, letters and reference signs appearing in the drawings
shall be simple and clear; brackets, circles and inverted commas
shall not be used in association with numbers and letters;
(e) elements of the same figure shall be in proportion to each other,
unless a difference in proportion is indispensable for the clarity
of the figure;
(f) the height of the numbers and letters shall not be less than 0.32
cm. and for the lettering of drawings, the Latin and, where
customary, the Greek alphabets shall be used;
(g) the same sheet of drawings may contain several figures;
(h) where figures drawn on two or more sheets are intended to form
one whole figure, the figures on the several sheets shall be so
arranged that the whole figure can be assembled without
concealing any part of the partial figures;
(i) different figures shall be arranged without wasting space and
shall be clearly separated from one another;
(j) different figures shall be numbered consecutively in Arabic
numerals, independently of the numbering of the sheets;
(k) reference signs not mentioned in the description or claims shall
not appear in the drawings and vice versa;
(l) the same features, when denoted by reference signs, shall,
throughout the application, be denoted by the same signs;
(m) the drawings shall not contain textual matter except, when