Leading lines are lines between reference signs and the details referred to. Such lines 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 at least as far as the features indicated.
Leading lines must be executed in the same way as lines in the drawing, viz. in accordance with Rule 46(2)(a).[Rule 46(2)(a); ]
Source: http://www.epo.org/law-practice/legal-texts/html/guidelines/e/a_ix_7_5_1.htm
Date retrieved: 17 May 2021