Section 28:9-501 - Filing office(a) Except as otherwise provided in subsection (b), if the local law of the District governs perfection of a security interest or agricultural lien, the office in which to file a financing statement to perfect the security interest or agricultural lien is: (1) The Recorder of Deeds, if: (A) The collateral is as-extracted collateral or timber to be cut; or(B) The financing statement is filed as a fixture filing and the collateral is goods that are or are to become fixtures; or(2) The Mayor in all other cases, including a case in which the collateral is goods that are or are to become fixtures and the financing statement is not filed as a fixture filing.(b) The office in which to file a financing statement to perfect a security interest in collateral, including fixtures, of a transmitting utility is the Office of the Mayor. The financing statement also constitutes a fixture filing as to the collateral indicated in the financing statement which is or is to become fixtures.Oct. 26, 2000, D.C. Law 13-201, § 101, 47 DCR 7576.