Draft Recommendation for Item 2 (Harold Solbrig)

Missing Value Reasons

nestingDepth	conceptCode	conceptName	description
1	NI	NoInformation	No information whatsoever can be inferred from this exceptional value. This is the most general exceptional value. It is also the default exceptional value.
2	MSK	masked	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.
2	NA	not applicable	No proper value is applicable in this context (e.g., last menstrual period for a male).
2	OTH	other	The actual value is not an element in the value domain of a variable. (e.g., concept not provided by required code system).
3	NINF	negative infinity	Negative infinity of numbers.
3	PINF	positive infinity	Positive infinity of numbers.
2	UNK	unknown	A proper value is (may be?) applicable, but not known.
3	NASK	not asked	This information has not been sought (e.g., patient was not asked)
		not sought	(synonym for NASK)
3	NDONE	not done	This procedure to acquire this result was not performed
3	NSPEC	not supplied by the source system	The source of the information didn't supply it for unspecified reasons.
3	TRC	trace	The content is greater than zero, but too small to be quantified.
3	ASKU	asked but unknown	Information was sought but not found (e.g., patient was asked but didn't know)
4	NAV	temporarily unavailable	Information is not available at this time but it is expected that it will be available later.