(a) Law governing priority. Revised Article 9 determines the priority of conflicting claims to collateral. However, if the relative priorities of the claims were established before Revised Article 9 takes effect, Former Article 9 determines priority.(b) Priority if security interest becomes enforceable under Section 9-203. For purposes of Section 9-322 (a), the priority of a security interest that becomes enforceable under Section 9-203 of Revised Article 9 dates from the time Revised Article 9 takes effect if the security interest is perfected under Revised Article 9 by the filing of a financing statement before Revised Article 9 takes effect which would not have been effective to perfect the security interest under Former Article 9. This subsection does not apply to conflicting security interests each of which is perfected by the filing of such a financing statement.