The UNDEF symbol: "Please feed me, I'm undefined (null)"

Throughout GreenDesk null values are used to represent values that are still undefined or have not yet been supplied. They are indicated by the symbol: UNDEF.

It usually indicates that some information may need to be provided, however it does not necessarily indicate an error state in your model unless GreenDesk additionally indicates that the value is both missing and required through the additional icon: .

So if you see this combination UNDEF, you'll know that the Expert System needs the value before a particular Credit, Activity, or related worksheet can be completed.