6. Matters Left to Other Provisions of This Article: Priority. With one exception, concerning goods covered by a certificate of title (see subsection (d) [Maine cite subsection (4)]), the other provisions of this Part, including the rules governing purchase-money security interests, determine the priority of most security interests in an accession, including the relative priority of a security interest in an accession and a security interest in the whole. See subsection (c) [Maine cite subsection (3)].

Example 3: Debtor owns an office computer subject to a security interest in favor of SP-1. Debtor acquires memory and grants a perfected security interest in the memory to SP-2. Debtor installs the memory in the computer, at which time (one assumes) SP-1's security interest attaches to the memory. The first-to-file-or-perfect rule of Section 9-322 [Maine cite section 9-1322] governs priority in the memory. If, however, SP- 2's security interest is a purchase-money security interest, Section 9-324(a) [Maine cite section 9-1324, subsection (1)] would afford priority in the memory to SP-2, regardless of which security interest was perfected first.

7. Goods Covered by Certificate of Title. This section does govern the priority of a security interest in an accession that is or becomes part of a whole that is subject to a security interest perfected by compliance with a certificate-of-title statute. Subsection (d) [Maine cite subsection (4)] provides that a security interest in the whole, perfected by compliance with a certificate-of-title statute, takes priority over a security interest in the accession. It enables a secured party to rely upon a certificate of title without having to check the UCC files to determine whether any components of the collateral may be encumbered. The subsection imposes a corresponding risk upon those who finance goods that may become part of goods covered by a certificate of title. In doing so, it reverses the priority that appeared reasonable to most pre-UCC courts.

Example 4: Debtor owns an automobile subject to a security interest in favor of SP-1. The security interest is perfected by notation on the certificate of title. Debtor buys tires subject to a perfected-by-filing purchase-money security interest in favor of SP-2 and mounts the tires on the automobile's wheels. If the security interest in the automobile attaches to the tires, then SP-1 acquires priority over SP-2. The same result would obtain if SP-1's security interest attached to the automobile and was perfected after the tires had been mounted on the wheels.