This document discusses using ETL Validator to test derived fields in target data by using transformation logic defined in source data. It provides step-by-step instructions to create a test case validating a 'cust_level' field derived in target based on logic in source. The test case executes the queries, identifies differences between target and transformed source data, and provides results that can be exported or viewed as a report. ETL Validator allows comprehensive testing of ETL processes through automation, repeatability, and validation of data across sources and targets.