Update for CF Version:68

"Volume fraction" is used in the construction "volume_fraction_of_X_in_Y", where X is a material constituent of Y. It is evaluated as the volume of X divided by the volume of Y (including X). It may be expressed as a fraction, a percentage, or any other dimensionless representation of a fraction. The phrase "frozen_water" means ice.

Sea water temperature is the in situ temperature of the sea water. The temperature at the sea floor is that adjacent to the ocean bottom, which would be the deepest grid cell in an ocean model.

A variable with the standard name of quality_flag contains an indication of assessed quality information of another data variable. The linkage between the data variable and the variable or variables with the standard_name of quality_flag is achieved using the ancillary_variables attribute.

A variable with the standard name of status_flag contains an indication of quality or other status of another data variable. This may include the status of the instrument producing the data as well as data quality information. The linkage between the data variable and the variable with the standard_name of status_flag is achieved using the ancillary_variables attribute. A variable which contains purely quality information may use the standard name of quality_flag to provide an assessed quality of the corresponding data.