7.5.4 Consistent use of reference signs in the description, claims and drawings 

Reference signs must be used in a manner which is consistent in the description, claims and drawings. In particular, reference signs not mentioned in the description must not appear in the drawings, and vice versa.

A feature denoted by a reference sign must be denoted by the same sign throughout the international application.

In the case of international applications dealing with complex subjects and incorporating a large number of drawings, a separate sheet listing all the reference signs should be included at the end of the description as a part of it.