The Auditor shall install and maintain suitable loose‑leaf systems in keeping bonded lien accounts and other such bookkeeping accounts which are required to be kept by the provisions of the Charter.  Such loose‑leaf accounts shall be kept in lock binders and shall be placed in lock book form upon completion of the record of such account.  Such loose‑leaf system installed in binders shall be deemed a permanent record for all purposes required by the Charter of the City.