The Arkansas Racing Commission adopted several amendments to its rules at a meeting Wednesday, including one that provides for the maximum toe grab height on front shoes to be increased from two to four millimeters. Another amendment allows superfecta wagering with at least seven betting interests. The minimum number of betting interests had been eight. The new rules go into effect Jan. 1. Oaklawn Park in Hot Springs, Ark., will open its meet Jan. 14. There were 504 horses on the grounds Friday morning, said David Longinotti, the assistant general manager of racing for the track. Published works are to begin Monday.