No information whatsoever can be inferred from this exceptional value. This is the most general exceptional value. It is also the default exceptional value.

The actual value is not an element in the value domain of a variable. (e.g., concept not provided by required code system).

Negative infinity of numbers.

Positive infinity of numbers.

A proper value is applicable, but not known.

Information was sought but not found (e.g., patient was asked but didn't know)

Information is not available at this time but it is expected that it will be available later.

This information has not been sought (e.g., patient was not asked)

The content is greater than zero, but too small to be quantified.

There is information on this item available but it has not been provided by the sender due to security, privacy or other reasons. There may be an alternate mechanism for gaining access to this information.

Note: using this null flavor does provide information that may be a breach of confidentiality, even though no detail data is provided. Its primary purpose is for those circumstances where it is necessary to inform the receiver that the information does exist without providing any detail.

No proper value is applicable in this context (e.g., last menstrual period for a male).

Value is not present in a message. This is only defined in messages, never in application data! All values not present in the message must be replaced by the applicable default, or no-information (NI) as the default of all defaults.