If your FileMaker Pro file accesses data from an ODBC data source, you can use
supplemental fields to define unstored calculations or summary instructions that act on data coming from the external sources. These fields display calculation and summary results in the FileMaker Pro file without changing the external database. For example, you can use supplemental fields to display aggregated data from an external file similarly to how you use summary fields to display aggregated data stored in FileMaker Pro files.