Bleed: how much of a disc may leave the page (50 % lets its centre sit on the edge). Big to centre: 0 mixes the sizes; 100 gathers the large discs in the middle, with medium and small mixed round them. Touch each side: at least that many discs touch every side (corners count); 0 leaves it to the packing. Tries: that many packings from the seed; the one with the smallest biggest hole is kept. Same settings and seed always give the same page.