Replacement mapping is an advanced feature that allows you to forcefully replace specific values in a web service request. For example, you could have a request with a POST body and a parameter called ‘super_secret,’ and any time that ‘super_secret’ has a value of ‘abc123,’ you want to replace it with ‘xxxxxx.’ In this case, you would add a mapping with an original value of ‘abc123’ and a new (replacement) value of ‘xxxxxx.’