ALE Programming Guide 
Use
You can add your own scenarios to the ALE business processes provided in the standard system.
Two programming models are provided for this purpose. These are differentiated by the type of message dispatched:
· Distribution Using BAPIs: This process has been supported since SAP Release 4.0A and is the basis for future developments.
· Distribution Using Message Types. ALE developments in SAP Release 3.x are based on this programming model.
In this guide you can find information about the following topics:
· Connection of External Systems
· Integration of Dialog Interfaces
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Notes on client copies:
When copying clients, any logical systems that have been defined for a client must also be converted in the header data of the copied documents, so that these documents can be found in the new client.
You can find more information about converting logical systems in the ALE Implementation Guide (transaction SALE) in path IDoc Interface / ALE -> Basic Settings -> Logical Systems -> Convert Logical System Names in Application Tables.
Recommended:
To avoid conversions of this type, application developers should ensure that when they create application documents, they do not fill the field with the logical name (value SPACE). The system automatically reads a field that is not filled as equal to the logical system of the current client.
When performing statistical evaluations of documents, the system checks that this field contains either the logical system of the current client or the value SPACE.
If these conditions are fulfilled, documents are regarded as belonging to the current client and are included in the statistical evaluation.