| COMARC/B | April | 2020 |
| 001 | Record label |
| 010 | International Standard Book Number |
| 011 | ISSN |
| 012 | Fingerprint identifier |
| 013 | International Standard Music Number (ISMN) |
| 016 | International Standard Recording Code (ISRC) |
| 017 | Other identifier |
| 020 | National bibliography number |
| 021 | Legal deposit number |
| 022 | Government publication number |
| 040 | CODEN |
| 041 | Other codes* |
| 071 | Publisher's number |
This block contains data that identify the record or the item recorded in it. Field 001 is mandatory in every record.