Hello, I was having a look at the ERD provided and case study and was wondering why the Customer subclass has the contactPhoneNumbers[1..3] attribute when in the case study it states: "Each patient or customer is uniquely identified by a client number (N 8) which is assigned to them when they first become associated with the clinic and is used for them thereafter. Also recorded are their name (C), address (A) and one to three contact phone numbers (S 14)."