This message type is sent by a custodian to a financial institution for which it holds securities.
It is used only to replace or supplement the certificate numbers field (field 35E or 35F) in a primary message and therefore can be sent only on the same day as that primary message.
| Status | Tag | Field Name | Content/Options | No. |
| M | 28 | Page Number/Continuation Indicator | 5n[/2n] | 1 |
| M | 20 | Transaction Reference Number | 16x | 2 |
| M | 21 | Related Reference | 16x | 3 |
| M | 35F | Certificate Number(s) | 35*50x | 4 |
There are no network validated rules for this message type.
When the MT 579 is used, the code /MSG579/ must be specified in field 72 of the primary message.
More than one MT 579 may be sent relating to the same primary message.