| http://www.opengis.net/def/nil/OGC/0/inapplicable | There is no value |
| http://www.opengis.net/def/nil/OGC/0/missing | The correct value is not readily available to the sender of this data. Furthermore, a correct value may not exist |
| http://www.opengis.net/def/nil/OGC/0/template | The value will be available later |
| http://www.opengis.net/def/nil/OGC/0/unknown | The correct value is not known to, or not computable by, the sender of this data. However, the correct value probably exists |
| http://www.opengis.net/def/nil/OGC/0/withheld | The value is not divulged |
| http://www.opengis.net/def/nil/OGC/0/AboveDetectionRange | Value was above the detection range of the instrument used to estimate it |
| http://www.opengis.net/def/nil/OGC/0/BelowDetectionRange | Value was below the detection range of the instrument used to estimate it |