Small nit; the PAX index values are not set by the SCCA, they are set informally and traditionally by Rick Ruth, an autocross competitor but not an official of any sort.
"This Index was developed by Rick Ruth and reflects results from over 30 large events including, the
Tire Rack® Solo II
National Championships, National Tour, Subaru
CenDiv,
Chicago Region SCCA,
Tri-State Sports Car Council and
Wisconsin Autocrossers Inc events. This index is designed to incorporate some of the previous PAX substance with the RTP Index of the past"