DataAbsentReason

Used to specify why the normally expected content of the data element is missing.

This value set has an inline code system http://hl7.org/fhir/data-absent-reason, which defines the following codes:

Lvl Code Display Definition Comments
1 unknown Unknown The value is not known.
1 asked Asked The source human does not know the value.
1 temp Temp There is reason to expect (from the workflow) that the value may become known.
1 not-asked Not Asked The workflow didn't lead to this value being known.
1 masked Masked The information is not available due to security, privacy or related reasons. Using "masked" may be breach of security or confidentiality, but there are times when its use is required to support alternate workflows for gaining access to denied information.
1 unsupported Unsupported The source system wasn't capable of supporting this element.
1 astext As Text The content of the data is represented in the resource narrative. it may be linked by internal references (e.g. xml:id). This usually implies that the value could not be represented in the correct format - this may be due to system limitations, or this particular data value
1 error Error Some system or workflow process error means that the information is not available.
2   NaN Not a Number NaN, standing for not a number, is a numeric data type value representing an undefined or unrepresentable value. This is sometimes ab output value from measuring devices