The Madrid to ED50 Polynomial transformation method allows for transformation of coordinates between the Madrid 1870 datum and the ED50 datum.
For a detailed reference on the Madrid to ED50 Polynomial transformation, refer to 2.3.1.3 "Polynomial transformation for Spain" in the EPSG Surveying and Positioning Guidance Note Number 7, part 2.
Note: This datum transformation has been computed for a specific area of use and specific datums. The base Datasource contains the standard datum transformations using this method. Creating new transformations using this method or using the transformation for data outside of the pre-determined envelopes may cause unreliable results.