134. Commission may publish guidelines. (1) The Commission may publish guidelines which clarify the meaning of "substantial lessening of competition". (2) The guidelines may include reference to— (a) the relevant economic market; (b) global trends in the relevant market; (c) the impact of the conduct on the number of competitors in a market and their market shares; (d) the impact of the conduct on barriers to entry into the market; (e) the impact of the conduct on the range of services in the market; (f) the impact of the conduct on the cost and profit structures in the market; and (g) any other matters which the Commission is satisfied are relevant. 135. Prohibition on entering into collusive agreements. A licensee shall not enter into any understanding, agreement or arrangement, whether legally enforceable or not, which provides for— (a) rate fixing; (b) market sharing; (c) boycott of a supplier of apparatus; or (d) boycott of another competitor. 136. Prohibition on tying or linking arrangements. A licensee shall not, at any time or in any circumstances, make it a condition for the provision or supply of a product or service in a communications market that the person acquiring such product or service in the communications market is also required to acquire or not to acquire any other product or service either from himself or from another person. 137. Determination of dominant licensee. The Commission may determine that a licensee is in a dominant position in a communications market. 138. Guidelines as to the meaning of "dominant position". (1) The Commission may publish guidelines which clarify how it will apply the test of "dominant position" to a licensee.