M - Indicates that microfilms may be substituted for retention of the original records at any time after use of the records for current recording purposes.
M - (with a numeral following) Indicates that microfilms may be substituted for retention of the original records only after the original records have been retained in their original form for at least the number of years corresponding to the numeral following the "M." Thus, "M-10" indicates that a microfilm copy may be made of and substituted for the original record only after the original record has been retained for at least ten years.
ME - Indicates records for which microfilms may be substituted for retention of the original records only for the period subsequent to the expiration, cancellation, supersedure or other condition shown in the column "Period to be Retained." Thus, for Item 9(e) of Appendix A, microfilms are not acceptable for current contracts; however, they are acceptable for expired or cancelled contracts, the retention period for which is three years after expiration or cancellation.
Ill. Admin. Code tit. 83, § 420.50