The rules in this subpart E of part 4000 tell you what methods you may use to meet any record retention requirement under our regulations if you choose to use electronic means. The rules for who must retain the records, how long the records must be maintained, and how records must be made available to us are contained in the specific part where the record retention requirement is found. (Subpart A tells you what filing methods you may use for filings with us and how we determine your filing date. Subpart B tells you what methods you may use to issue a notice or otherwise provide information to any person other than us. Subpart C tells you how we determine your filing or issuance date. Subpart D tells you how to compute various periods of time.)