When you configure masking rule properties, you can configure preprocessing and postprocessing expressions.
For each masking rule that you create, you can specify preprocessing and postprocessing expression parameters to apply changes before and after masking the data. A preprocessing expression defines the changes that you want to make to the data before masking. A postprocessing expression defines the changes that you want to make to the masked data before saving the data to the target. Use the expression builder to create an expression.
For example, the AccountName field can contain the name JOHN in uppercase and John in lowercase alphabetic characters. If you apply a masking technique and run the task, the task masks the same name with different values. If you want the same masked value in the target for both the names, you can apply preprocessing expression to convert all the uppercase alphabetic characters to lowercase. Use repeatable masking technique to mask with same values. To convert the masked values to uppercase alphabetic characters, apply postprocessing expression.
You cannot configure preprocessing and postprocessing expressions for custom masking.