This is a petition for review of the validity of two rules promulgated by the Oregon Liquor Control Commission (OLCC).1 The sole question is whether the *559rules exceed the statutory authority of OLCC.2 ORS 183.400(4)(b).
The authority of the OLCC to enact implementing regulations is contained in several statutory provisions. The Liquor Control Act (ORS ch 471) is to be "liberally construed so as to protect the safety, welfare, health, peace and morals of the people of the state.” ORS 471.030(l)(c). In addition to specifically enumerated powers and duties, the commission has the powers "necessary and proper to enable it to carry out fully and effectually all the purposes of this chapter.” ORS 471.040. The commission is empowered "to adopt such regulations as are necessary and feasible for carrying out the provisions of [the Act]” and "to exercise all powers incidental, convenient or necessary to enable it to administer or carry out any of the ’provisions of [the Act].” ORS 471.730(6). Broad delegation of authority to the OLCC has been judicially *560recognized. See Van Ripper v. OLCC, 228 Or 581, 590, 365 P2d 109 (1961); McCann v. OLCC, 27 Or App 487, 493, 556 P2d 973 (1976), rev den (1977).
The challenged rules, which concern beer and wine pricing practices, embody three features to which petitioners object. First, quantity discounts are prohibited. OAR 845-10-210(l)(a) and (2)(a). Second, prices must be posted 10 days prior to their taking effect, and prices reflecting a price decrease generally remain effective after posting for a period of 180 days for malt beverages and 30 days for wine. OAR 845-10-210(l)(c) and (d), and (2)(c) and (d). Third, regardless of transportation arrangements, the prices must be those posted, thus eliminating the giving of transportation allowances. OAR 845-10-211.
Petitioners characterize those features of the challenged rules (which we assume for the purpose of this review are aptly summarized above) as having a price-fixing or price-stabilizing effect tending to discourage competition.3 That issue is not before this court. We can only determine whether the challenged rules reasonably advance a statutory purpose. See Van Ripper v. OLCC, supra at 591; Fred Meyer v. Bureau of Labor, 39 Or App 253, 268, 592 P2d 564 (1978), rev den 287 Or 129 (1979).
The statutory authority relied upon by the OLCC with respect to the challenged rules is ORS 471.465,4 *561prohibiting financial assistance to retailers. We note preliminarily that an agency’s interpretation of its statutory authority is entitled to deference by the courts, and we cannot substitute our policy ideas for those of the agency. Van Ripper v. OLCC, supra at 593; Duncan v. Law Enforcement Council, 37 Or App 119, 123, 586 P2d 398, rev den 285 Or 195 (1978).
Petitioners assert that the phrase "other than merchandise sold in the usual course of trade” in ORS 471.465 categorically exempts any transaction involving such merchandise. Although the phrase presents grammatical problems, we do not understand it to have the suggested effect because that would effectively destroy the evident objective of the entire section. The most sensible reading is that selling merchandise to a licensee for use in the licensee’s business cannot by itself be a violation of the statute.5 The discount, price posting and delivered price features of the rules in question appear to be reasonably designed to prevent financial assistance proscribed under ORS 471.465 in the form of special allowances or discounts to retail licensees.
In addition to ORS 471.465, the Liquor Control Act contains several "tied-house” provisions6 designed to *562separate possible wholesale and retail financial connections, a purpose sought to be achieved in part by the challenged rules. Finally, the anti-discriminatory thrust of the Oregon constitutional amendment concerning the sale of liquor7 and of the financial assistance statute discussed above is reasonably advanced by these rules by ensuring that beer and wine prices will be the same for all retailers.
Rules upheld.