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FioriApp:Create Billing Documents(F0798)
From SAP Knowledge Base
Function "Display billig document after creation"
If this function is activated in the billing settings in the app, a temporary billing document will be created after selecting an item and clicking the 'Create invoices' button.
If the number range prefix 'TMP' and the corresponding interval are not maintained in customizing, a error message appears.
Note 2922052 describes what to do.