What is the first step to transform a CSV field before mapping it to an XDM field?

The correct first step to transform a CSV field before mapping it to an XDM field is to add a calculated item in the mapper workspace. This action is essential because it allows you to create a new field based on the existing data from the CSV. This transformation is crucial in ensuring that the data aligns properly with the expected format of the XDM fields, which may require specific data types or structures.

When you add a calculated item, you can leverage functions to manipulate the data as needed, such as concatenating strings, converting data types, or performing arithmetic operations. This preprocessing step is fundamental in preparing your data to meet the requirements of Adobe Experience Platform efficiently, ensuring that the final mapping accurately reflects the intended data structure.

Choosing to remove the field when it has been automatically mapped does not provide the opportunity to transform the data, nor does it utilize the features available in the mapper workspace which are necessary for an effective data transformation.