For these purposes, the retrospective periods in   WBF  2021 Anti -Doping Rules  Page 59 of 67    which prior violations can be considered for purposes of multiple violations under Article 10.9.4 and the statute of limitations set forth in Articl e 16 are procedural rules, not substantive rules, and should be applied retroactively along with all of the other procedural rules in these Anti -Doping Rules (provided, however, that Article 1 6 shall only be applied retroactively if the statute of limitati on period has not already expired by the Effective Date).