The names assigned to map fields in the map's source file are the names referenced by the Map Annotations Editor and the Interface Mapper as logical field names, with one exception. For CICS BMS maps, if the field name is a reserved COBOL word, -Reserved is appended to the field name.
You can change a logical field name to something that more clearly identifies the field. When you use the Service Interface Editor to create mappings with screen fields, having an easily recognized logical name for each field can be quite helpful, especially if the screen field names defined in the map's source file are somewhat cryptic.