Alphanumeric phone numbers were used in Canada until the 1960s. Many of the phone numbers listed in the advertisements within this cookbook utilize the 2 Letter-5 Number (2L-5N) phone number format. The two letters were used to indicate the region one was located in, and the numbers were used to allow for different numbers for the individuals in a region. Eventually, the quantity of phone numbers needed was greater than what could be created with the given format. Subsequently, in the 1960s there was a transition to strictly numeric phone numbers, with more digits added for increased combination possibilities.