A list of available document numbers is maintained by Herschel. This holds details of all the available purchase order, sales order, works order, sales credit, purchase return, purchase receipt, despatch note, nonconformance report and quotation numbers. As each of these documents is raised, Herschel checks the order log to determine the next number to use.
Occasionally you may try to create a new document, but Herschel will warn you there are no free document numbers available.
New numbers can be added with the Manager module's add more documents option. This allows you to control how many documents your staff can create. If this isn't an issue in your business, you can add a large number of document numbers to avoid running out in the future: