| Segment specification | UNT |
| Directory | Messages | Segments | Composites | Data elements | Codes | Meaning of the change indicators |
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| —————————————————————————————————————————————— |
| 010 |
|
0074 | Number of segments in the message | M | 1 | n..6 | |||
| 020 |
|
0062 | Message reference number | M | 1 | an..14 |
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