Section 9--315. Secured  Party's Rights on Disposition of Collateral and in Proceeds. (a) Disposition of collateral: continuation of  security  interest  or  agricultural  lien;  proceeds.  Except  as  otherwise  provided  in this  article and in Section 2--403(2): (1) a  security  interest  or  agricultural  lien  continues in collateral notwithstanding sale, lease, license, exchange, or other disposition thereof unless the secured party authorized the disposition free of the security interest or agricultural lien; and (2) a  security interest attaches to any identifiable proceeds of collateral. (b) When  commingled  proceeds identifiable. Proceeds that are  commingled with other property are identifiable proceeds: (1) if  the proceeds are goods, to the extent provided by Section 9--336; and (2) if the proceeds are not goods, to the extent that the secured party  identifies  the  proceeds  by  a  method  of  tracing, including application  of  equitable  principles,  that  is permitted under law other than this article with  respect  to commingled property of the type involved. (c) Perfection  of  security interest in proceeds. A security interest  in proceeds is a perfected security interest if the security interest in  the original collateral was perfected. (d) Continuation of  perfection.  A  perfected  security  interest  in  proceeds becomes unperfected on the 21st day after the security interest  attaches to the proceeds unless: (1) the following conditions are satisfied: (A) a filed financing statement covers  the  original collateral; (B) the proceeds are collateral in which a security  interest may  be  perfected  by  filing in the office in which the financing statement has been filed; and (C) the proceeds are not acquired with cash proceeds; (2) the proceeds are identifiable cash proceeds; or (3) the security interest in the proceeds is perfected other than under subsection (c) when the security interest  attaches  to the proceeds or within 20 days thereafter. (e) When  perfected security interest in proceeds becomes unperfected.  If a  filed  financing  statement  covers  the  original  collateral,  a  security  interest  in proceeds which remains perfected under subsection  (d)(1) becomes unperfected at the later of: (1) when the  effectiveness  of  the  filed  financing  statement lapses  under  Section  9--515 or is terminated under Section 9--513; or (2) the 21st day after the  security  interest  attaches  to  the proceeds.