Report/Patent number (M Level)
Enter in this field any report numbers given on the resource. Report numbers may be standardized. If more than one report number is assigned, they may be entered in repeating Identifier fields

APO-Project: SYS- -4/71
French patent document: 2037368/B/

Occasionally a report is issued in several parts or in several editions. The relevant statement is then made in parentheses immediately after the report number using the following list of abbreviations.
TID--2236 (pt.1)

For more information see the cataloguing manual under: Identifiers