The occurrence column in the specifications determines which information is mandatory or optional. The possible values and their description can be found in the table below.
| Occurrence Indicator | Description | Mandatory / Optional |
|---|---|---|
| 1 | One element | Mandatory |
| 1..n | One or multiple elements | Mandatory |
| 0..1 | Zero or one element | Optional |
| 0..n | Zero or one or multiple elements | Optional |