To define billing series we can go to:
System -> Economic Aux.-> Invoicing Serial number
Then the following window will open:
Here you can see all the billing series defined in the system.
For example, Series A may be used for memberships, while Series R is used for bookings.
Both the series and their descriptions are configured according to your needs. When generating invoices, this classification helps keep products organized and prevents them from being mixed together.
If you want to edit any of them, click the edit icon, and the following window will open:
From here, you can define your Membership Series, as well as its formats, or modify its description.