As an IPF Member nation, the CPU follows the IPF's technical rules, which can be seen on the IPF site.
"21 Days" Rule
The CPU will now follow the "21 Days" Rule, for National and Regional Championships Only. IPF rules state that competitors may not change their nominated weight and age class within 21 days of the event, meaning that you cannot lift if you do not make that weight class. At any other CPU contest in Canada the CPU does not observe this, weight or age classes may be changed at any time, including following the weigh-in.