| Code | Display | Definition |
| high | High quality | High quality evidence. |
| moderate | Moderate quality | Moderate quality evidence. |
| low | Low quality | Low quality evidence. |
| very-low | Very low quality | Very low quality evidence. |
| no-concern | no serious concern | no serious concern. |
| serious-concern | serious concern | serious concern. |
| very-serious-concern | very serious concern | very serious concern. |
| extremely-serious-concern | extremely serious concern | extremely serious concern. |
| present | present | possible reason for increasing quality rating was checked and found to be present. |
| absent | absent | possible reason for increasing quality rating was checked and found to be absent. |
| no-change | no change to rating | no change to quality rating. |
| downcode1 | reduce rating: -1 | reduce quality rating by 1. |
| downcode2 | reduce rating: -2 | reduce quality rating by 2. |
| downcode3 | reduce rating: -3 | reduce quality rating by 3. |
| upcode1 | increase rating: +1 | increase quality rating by 1. |
| upcode2 | increase rating: +2 | increase quality rating by 2. |