| numberOfDataPoints | This is the total number of points on the grid and includes missing as well as 'real' values |
| numberOfValues (=numberOfCodedValues) | These two keys are the same (one is an alias for the other). This is the number of 'real' values in the field and excludes the number of missing ones |
| numberOfMissing | The number of missing values in the field |
So you can write the equation:
numberOfDataPoints = numberOfCodedValues + numberOfMissing