An Address Type is a generic description for an address entry of any customer, not a specific name for a particular address of a particular customer.
Address Types apply to all customers. That is, if you create an address type in one customer, that address type will also show in the Address Type popdown list for every customer.
A customer can use a particular Address Type only once. For example, a customer cannot have two different addresses both marked as Receiving Dock. However, a second different customer can have its own Receiving Dock address, which has a different (physical) address from the first customer's Receiving Dock.
Creating and editing Address Types are combined into one interface, which may make these processes confusing. If you're having trouble, try editing only the Address Type or the address info (below) but not both, then saving the customer (with the green Save button). Then edit the customer and address again, changing the next part as desired.
While a larger number of Address Types may be created (up to 60 have been observed), each customer can have only 10 or 11 addresses before receiving an error when trying to add another.
When a new Address Type is created, it is added to the list, but there is no way to delete existing ones at this time.