(a) The registrar shall maintain a file containing the approved registration applications of the registered voters of the county.
(b) The registrar shall maintain the file in alphabetical order by voter name on a countywide basis. However, the registrar may maintain the file in numerical order by registration number if the registrar regularly maintains a list of registered voters in alphabetical order by voter name on a countywide basis.
(c) Each application shall be retained on file during the time the registration is effective.