For each message type you create, you must specify the purpose for which it is to be used. For example, outputting (printing/transmission) of new documents, outputting of change documents, outputting of urging messages (expediters).

You make the settings for fine-tuned control with regard to the various message types in Customizing for Purchasing.

If you wish to use different message types for each type of scheduling agreement release, you should specify which message type updates the print-relevant data (e.g. date of last transmission).