https://userapps.support.sap.com/sap/support/knowledge/en/3047012
3047012 - ADSO warning Extending a field of type NUMC is not allowed | SAP Knowledge Base Article
While trying to extend a field of type NUMC the following warning, error: Field XYZ: Extending a field of type NUMC is not allowed RSO_RES_ADSO 266