4. The rules of this section operate in favor of whichever party to the lease contract may enforce it, even if one party perhaps may not, e.g., under Section 2A-201(1)(b).

5. The rules stated in subsections (2)(b) and (c), and the rule in subsection (3), are is best understood by reviewing a hypothetical. Assume that a merchant engaged in the business of selling and leasing musical instruments obtained possession of a truck load of musical instruments on deferred payment terms from a supplier of musical instruments on January 6. To secure payment of such credit the merchant granted the supplier a security interest in the instruments; the security interest was perfected by filing on January 15. The merchant, as lessor, entered into a lease to an individual of one of the musical instruments supplied by the supplier; the lease became enforceable on January 10. Under subsection (2)(b) the lessee will prevail (assuming the lessee qualifies thereunder) unless subsection (c) provides otherwise. Under the rule stated in subsection (2)(c) a priority dispute between the supplier, as the lessor's secured creditor, and the lessee would be determined by ascertaining on January 10 (the day the lease became enforceable) the validity and perfected status of the security interest in the musical instrument and the enforceability of the lease contract by the lessee. Nothing more appearing, under the rule stated in subsection (2)(c), the supplier's security interest in the musical instrument would not have priority over the lease contract. Moreover, subsection (2) states that its rules are subject to the rules of subsections (3) and (4). Under this hypothetical the lessee should qualify as a "lessee in the ordinary course of business". Section 2A-103(1)(o). Subsection (3) also makes clear that the lessee in the ordinary course of business will win even if he or she knows of the existence of the supplier's security interest.

6. Subsections (3) and (4), which are modeled on the provisions of Section 9-307(1) and (3), respectively, state two exceptions to the priority rule stated in subsection (2) with respect to a creditor who holds a security interest. The lessee in the ordinary course of business will be treated in the same fashion as the buyer in the ordinary course of business, given a