Краткое пояснение: The legend on the map provides a key to understanding the symbols used. The dotted line is explicitly defined in this legend.
Решение:
- The legend (Условные знаки) lists different symbols and their meanings.
- The first item in the legend shows a dotted line followed by the text "граница Российской Федерации".
Ответ: The dotted line represents the border of the Russian Federation.