51. For the purposes of this Division, “payment period” means a space of time, computed in days, that extends inclusively from the date from which the credit charges are payable to the date of the first payment and, subsequently, inclusively from the day following the date of a payment to the date on which the following payment is made.
R.R.Q., 1981, c. P-40.1, r. 1, s. 51.