A masking rule defines the logic that masks the data.
The type of masking rule that you can apply depends on the data type of the field that you need to mask. For example, if the field data type is numeric, you can define a masked value that is within a fixed or percent variance from the original value.
You can restrict the characters in a string to replace and the characters to apply in the mask. You can provide a range of numbers to mask numbers and dates.