| Lvl | Code | Display | Definition |
| 1 | unknown | Unknown | The value is expected to exist but is not known. |
| 2 | asked-unknown | Asked But Unknown | The source was asked but does not know the value. |
| 2 | temp-unknown | Temporarily Unknown | There is reason to expect (from the workflow) that the value may become known. |
| 2 | not-asked | Not Asked | The workflow didn't lead to this value being known. |
| 2 | asked-declined | Asked But Declined | The source was asked but declined to answer. |
| 2 | asked-unknown | Asked But Unknown | The source was asked but does not know the value. |
| 2 | temp-unknown | Temporarily Unknown | There is reason to expect (from the workflow) that the value may become known. |
| 2 | not-asked | Not Asked | The workflow didn't lead to this value being known. |
| 2 | asked-declined | Asked But Declined | The source was asked but declined to answer. |
| 1 | masked | Masked | The information is not available due to security, privacy or related reasons. |
| 1 | not-applicable | Not Applicable | There is no proper value for this element (e.g. last menstrual period for a male). |
| 1 | unsupported | Unsupported | The source system wasn't capable of supporting this element. |
| 1 | as-text | As Text | The content of the data is represented in the resource narrative. |
| 1 | error | Error | Some system or workflow process error means that the information is not available. |
| 2 | not-a-number | Not a Number (NaN) | The numeric value is undefined or unrepresentable due to a floating point processing error. |
| 2 | negative-infinity | Negative Infinity (NINF) | The numeric value is excessively low and unrepresentable due to a floating point processing error. |
| 2 | positive-infinity | Positive Infinity (PINF) | The numeric value is excessively high and unrepresentable due to a floating point processing error. |
| 2 | not-a-number | Not a Number (NaN) | The numeric value is undefined or unrepresentable due to a floating point processing error. |
| 2 | negative-infinity | Negative Infinity (NINF) | The numeric value is excessively low and unrepresentable due to a floating point processing error. |
| 2 | positive-infinity | Positive Infinity (PINF) | The numeric value is excessively high and unrepresentable due to a floating point processing error. |
| 1 | not-performed | Not Performed | The value is not available because the observation procedure (test, etc.) was not performed. |
| 1 | not-permitted | Not Permitted | The value is not permitted in this context (e.g. due to profiles, or the base data types). |