Kuril Islands dispute

The Kuril Islands dispute is a dispute between Japan and the Russian Federation over sovereignty over the South Kuril Islands. One of the disputed points is the border of the Kuril Islands. The San Francisco Peace Treaty between the Allied Powers and Japan from 1951 states that Japan must give up all claims to the Kuril islands. Japan claims that the disputed four islands are not a part of the Kuril Islands, and thus are not covered by the treaty. Russia disagrees.

I wonder why they didn’t use a map to avoid the ambiguity. Is it usual not to use a map at a treaty that decides borders between two countries ?