; (IX) (aa) is registered with the Federal Communications Commission under the Antenna Structure Registration program set forth under part 17 of title 47, Code of Federal Regulations; and (bb) is determined by the Administrator to pose no hazard to air navigation; or (X) has already mitigated any hazard to aviation safety in accordance with Federal Aviation Administration guidance or as otherwise approved by the Administrator. (B) Rural area The term rural area has the meaning given the term in section 609(a)(5) of the Public Utility Regulatory Policies Act of 1978 ( 7 U.S.C. 918c(a)(5) ). (C) Agricultural purposes The term agricultural purposes means farming in all its branches and the cultivation and tillage of the soil, the production, cultivation, growing, and harvesting of any agricultural or horticultural commodities performed by a farmer or on a farm, or on pasture land or rangeland. (2) Other definitions The Administrator shall define such other terms as may be necessary to carry out this section. (c) Database The Administrator shall— (1) develop a new database, or if appropriate use an existing database that meets the requirements under this section, that contains the location and height of each covered tower that, pursuant to subsection (a), the owner or operator of such tower elects not to mark (unless the Administrator has determined that there is a significant safety risk requiring that the tower be marked), except that meteorological evaluation towers shall be marked and contained in the database; (2) keep the database current to the extent practicable; (3) ensure that any proprietary information in the database is protected from disclosure in accordance with law; (4) ensure that, by virtue of accessing the database, users agree and acknowledge that information in the database— (A) may only be used for aviation safety purposes