When you configure key or random masking for string data type, configure target filter characters to limit the characters that appear in a target column.
The Data Masking transformation replaces characters in the target with the target filter characters. For example, enter the following characters to configure each mask to contain all uppercase alphabetic characters:
To avoid generating the same output for different input values, configure a wide range of substitute characters or mask only a few source characters. The position of each character in the string does not matter.