If you are familiar with the predefined method you want to use, and your expression algorithm is solely a call to that method, an alternative approach is available. The System Reference describes pre-defined methods in detail.
You can select the function directly from the Method column on the Mapping tab, which lists all the predefined functions. Then click Edit source.
In the Mapping Methods Parameters dialog, you then define values for the method parameters.
This was the only available option for invoking a predefined method in earlier versions of Connect CDC. Using the option described in the preceding example is recommended because it offers immediate validation of your parameter specifications.