The Customer Contact Site List form opens when you click the the Customer Contact Site button in Customer Ship To Information. This form will list each Customer ID that you have entered either a Contact or Site record for. You would initially setup the Customer Contact Site and Departments in the Customer form for a specific customer. Then, this form will display a line item of information for each Customer and the total number of Contact and Sites for every customer.
If you click on the ellipse button to the left of a specific Customer ID or line item, the Customer Contact Sites and Departments form will open, which will allow you to view the contacts and sites as well as additional information.