An IDoc consists of a control record with the structure edidc and one or more data records with the structure edidd. The control record is similar to an envelope. It contains the sender and receiver of the IDoc, as well as information about the type of message. The data that is being used by the IDoc is contained in the data records as unformatted character strings.

To be able to pass an IDoc to the ALE layer, you must set up a structure with the structure edidc and an internal table with the structure edidd. This is then used to call function module MASTER_IDOC_DISTRIBUTE. The module saves the data to the database and if necessary triggers dispatch.

All ALE message flows are stored in the ALE distribution model. The distribution model is the central controlling instance for ALE. The application can query the distribution model before the IDoc is created. This makes sense if the actual creation of an IDoc influences the application. Since you are not required to set up the internal table for the IDoc when no message flow is maintained in the distribution model, it can also improve performance.

The ALE layer always queries the distribution model. If the application does not specify a receiver, all receivers are determined and an IDoc is created for each one. If the application does specify a receiver, the distribution model is checked to see whether the receiver has the necessary authorization. Due to the filter settings in the distribution model, parts of the IDoc can be removed in the ALE layer.