When you set the payment term for a customer as '0' (zero) day in the Debtor control, it will print on the invoice as '0' day as default if the Term field has added to the form template. The Invoice due date is calculated based on the value set in the Term field of the name profile, therefore only numeric is acceptable. For example, when you issued an invoice dated as 1st January and the Term set is 'Within Days 30', the due date of the invoice will be 31st January.
Although you cannot change the field setting, you can modify the print. An 'if()' function can be added to the invoice template if you prefer to name the payment term as instant, immediate, C.0.D. (Cash on Delivery), etc. instead of '0-days' when printed.
Let's say you prefer 'immediate' than 0-day, then add an if() into the payment term field from the form designer:
if (Name.DebtorTerms = "0", "Immediate", Name.DebtorTerms + " Days")
The above will tell MoneyWorks to print the term as 'immediate' if the term set in the name profile is '0', or else print as the value set in the term field and add the text ' Days" behind it. In short, MoneyWorks will print as 'immediate' if the term is '0' and '30 Days" if the term is 30.
There are sample forms available which you can use or amend to suit your business. You can also create a new one from the File menu. Refer to the Forms Designer chapter on MoneyWorks User Guide to learn more about form design or get a Consultant to design a form for you.