GRID_DIAGONALS: Readonly<
    {
        ALTERNATING_1: 4;
        ALTERNATING_2: 5;
        APPROXIMATE: 2;
        EQUIDISTANT: 0;
        EXACT: 1;
        ILLEGAL: 6;
        RECTILINEAR: 3;
    },
> = ...

The different rules to define and measure diagonal distance/cost in a square grid. The description of each option refers to the distance/cost of moving diagonally relative to the distance/cost of a horizontal or vertical move.