The need for qualitatively distinguishable limits that enjoy some kind of uniqueness is especially enhanced by the fact that limits are generally found by a process of tacit maneuver and negotiation. They are jockeyed for, rather than negotiated explicitly. But if the two sides must strike a "bargain" without explicit communication, the particular limit has to have some quality that distinguishes it from the continuum of possible alternatives; otherwise there is little basis for the confidence of each side that the other acknowledges the same limit. Even a parallel of latitude, or an international date line, or the north pole, may have this quality when no other natural, plausible, "obvious" point or line is available for expectations to converge on.

XREF: Echoes Schelling's focal-point theory of tacit coordination — limits converge where some salient, qualitatively distinct anchor exists.

Thomas C. Schelling, The Strategy of Conflict, loc. 600