| Value | Category |
|---|---|
| 1 | Present most or all nights |
| 2 | Present during working days but away most weekends |
| 3 | Present during weekends but away during working days |
| 4 | Present about once a month |
| 5 | Present for one or two periods in the year |
| 6 | Present during school holidays |
| 7 | Other |