APPENDIX H:
HL7 FLAVORS OF NULL TABLE
Definition: If a value is an exceptional value (NULL-value), this specifies in what way and why proper information is missing.
| NAACCR Code | HL7 Code | Name | Definition |
| 10 | NI | no information | No information whatsoever can be inferred from this exceptional value. This is the most general exceptional value. It is also the default exceptional value. It is unknown whether this event occurred (e.g., radiation treatment). |
| 11 | NA | not applicable | No proper value is applicable in this context (e.g., last menstrual period for a male). |
| 12 | UNK | unknown | A proper value is applicable but not known. This event occurred, but the date is unknown (e.g., birth date). |
| 13 | NASK | not asked | This information has not been sought (i.e., patient was not asked). |
| 14 | ASKU | asked but unknown | Information was sought but not found (i.e., patient was asked but did not know). |
| 15 | NAV | temporarily unavailable | Information is not available at this time, but it is expected that it will be available later. |
| 16 | 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). |
| 17 | PINF | positive infinity | Positive infinity of numbers. |
| 18 | NINF | negative infinity | Negative infinity of numbers. |
| 19 | MSK | masked | Information on this item is available, but it has not been provided by the sender due to security, privacy, or other reasons. An alternate mechanism for gaining access to this information may be available. Note: Using this null flavor does provide information that may be a breach of confidentiality. Its primary purpose is for those circumstances where it is necessary to inform the receiver that the information does exist. |
| 20 | NP | not present | 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. |
The null flavors are a general domain extension of all normal data types. Note the distinction between value domain of any data type and the vocabulary domain of coded data types. A vocabulary domain is a value domain for coded values, but not all value domains are vocabulary domains.
* The null flavor Other is used whenever the actual value is not in the required value domain. This may be, for example, when the value exceeds some constraints that are defined too restrictively (e.g., age < 100 years).
Note: Null flavors are applicable to any property of a data value or a higher-level object attribute. Where the difference of null flavors is not significant, ITs are not required to represent them. If nothing else is noted in this specification, ITs need not represent general NULL flavors for data-value property.