...
Opaqueness percentage that is used to display missing values (NaN values) for point locations and tracks. This overrules the opaqueness of the configured missingValueColor. If missingValueOpaquenessPercentage is not configured, then opaqueness of missingValueColor is used. When labels are shown in the display for cells or locations/polygons for timesteps with missing values, NaN is shown as label. When you do not want the label to contain NaN values, use a missingValueOpaquenessPercentage of 0.
unitVisible (available since build 18734)
...