; and (2) not be altered in such a way as to decrease the machine-readable nature of the open Government data. (b) Alteration of digital location, format, or content (1) In general It shall not be a violation of subsection (a) to alter— (A) the digital location or format of open Government data for the purpose of routine asset maintenance or long-term archiving if the alteration does not decrease the open public accessibility or the machine-readable nature of the open Government data; or (B) the contents of open Government data for purposes of updating the open Government data or correcting an error in the open Government data. (2) Permanence of data after updates For purposes of subsection (a), any alteration of the digital location, format, or contents of open Government data under subparagraph (A) or (B) of paragraph (1) shall not constitute a renewal of the period for which the open Government data has been made available to the public. (3) Record of data changes after updates Any substantial alteration of the contents of open Government data under subparagraph (A) or (B) of paragraph (1) shall be recorded in a log that is made available to the public in an open format along with the open Government data. (c) Exceptions (1) Conservation of agency resources An agency may remove open Government data from public availability if— (A) the head of the agency determines that the open Government data— (i) is too costly to maintain; or (ii) does not provide sufficient value to the public; (B) not less than 6 months before the date on which the agency removes the open Government data from public availability, the agency publishes a notice of the removal in the Federal Register, including— (i) a clear identification of the open Government data; (ii) if applicable, the digital object identifier of the open Government data; (iii) a detailed description of the reasons for the removal; and (iv) a detailed description of efforts to make the open Government data permanently publicly available