Hello , by Sudhir Mishra Arya, thank you for your reply. I have the link open. I have the code inserted into a file, which I costumer_sequence.xml I have called. Hope that is so far right? Unfortunately, I do not yet quite clear where I must save this file, because a search under Windows multiple folders and files.

You must put that file in your module in which you want to use that sequence.

Sorry, because I must ask over again. As already mentioned, unfortunately, I do not have too much notion which module I for the customers - not Lieferanten-nehem must go. I suppose that it is the sales module, however, am not sure, whether it not, nevertheless, a module gubt in which contacts are treated in general. A more precise statement would be more helpful.