sector line

A sector line is a notional line separating two strategic sectors of the board, often lying between opposing frameworks or spheres of influence. It is not drawn by placing stones: players infer it from the position and strength of the surrounding stones, and its location may shift as the position develops.

The line helps assess the balance between opposing frameworks, territorial prospects, and the direction of play. It is a strategic guideline rather than a fixed board line or a guaranteed territorial boundary. Because it is approximate, its value depends on factors such as stone strength, nearby weak groups, and tactical possibilities. A sector line should therefore guide judgment, not replace reading the concrete position.