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

# concept[].definition
The value is expected to exist but is not known.

# concept[].concept[].definition
The source was asked but does not know the value.

# concept[].concept[].definition
There is reason to expect (from the workflow) that the value may become known.

# concept[].concept[].definition
The workflow didn't lead to this value being known.

# concept[].concept[].definition
The source was asked but declined to answer.

# concept[].extension[].valueString
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.

# concept[].definition
The information is not available due to security, privacy or related reasons.

# concept[].definition
There is no proper value for this element (e.g. last menstrual period for a male).

# concept[].definition
The source system wasn't capable of supporting this element.

# concept[].extension[].valueString
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.

# concept[].definition
The content of the data is represented in the resource narrative.

# concept[].definition
Some system or workflow process error means that the information is not available.

# concept[].concept[].extension[].valueString
This is sometimes an output value from measuring devices.

# concept[].concept[].definition
The numeric value is undefined or unrepresentable due to a floating point processing error.

# concept[].concept[].extension[].valueString
This is sometimes an output value from measuring devices.

# concept[].concept[].definition
The numeric value is excessively low and unrepresentable due to a floating point processing error.

# concept[].concept[].extension[].valueString
This is sometimes an output value from measuring devices.

# concept[].concept[].definition
The numeric value is excessively high and unrepresentable due to a floating point processing error.

# concept[].definition
The value is not available because the observation procedure (test, etc.) was not performed.

# concept[].extension[].valueString
This is most often associated with required bindings that do not include the actual code used, but may be used with other data types.

# concept[].definition
The value is not permitted in this context (e.g. due to profiles, or the base data types).