(1) A buyer or seller is not represented by a brokerage in a regulated real estate transaction unless the buyer or seller and the brokerage agree, in a separate written document, to such representation. No type of agency representation may be assumed by a brokerage, buyer or seller or created orally or by implication.
(2)  Types of brokerage relationships. The following types of brokerage relationships are recognized:
(a)  Nonagency;
(b)  Agency representation;
(c)  Limited dual agency representation;
(d)  Limited dual agency with assigned agents.