7. The method as described in claim 3 , wherein the step (b) further comprises introducing one, two or three patent indices.
7. The method as described in claim 3 , wherein the step (b) further comprises introducing one, two or three patent indices. 11. The method as described in claim 7 , wherein the step (c) further comprises assigning a color to a patent document according to a color model, whose number of components equals the number of patent indices, and wherein values of the components of the color model are equal to respective values of patent indices characterizing the patent document.