Using field overlays

Field overlays are a type of field reference that requests the copying of multiple fields from the source record layout to the target record layout. Field overlays reference one, or potentially, many source fields. The first field reference in the overlay is the starting position in the source layout. The reference is specified by field numbers separated by a hyphen ( - ). The cumulative length of the referenced fields is the length of the data to be moved. This length includes slack bytes inserted between fields. The data is moved from the starting position for the length into the target record layout starting at the field specified.

Since no validation is performed, you can create invalid data in the target fields. This may be desirable in some cases. You can use a field overlay to request the copying of data between different field types. For example, an unsupported data field can be moved to another field type.