Advanced Collections Metrics

Hi,

I have noticed that Advanced Collections comes with a number of seeded Metrics which can be used at difference operational levels (Customer, Account & Bill To).

It would also appear that these seeded metrics are calling Functions to derive a value returned in the Collections workbench.

I tried setting up a new metric at the Bill To level with just a simple SQL statement (select trunc(sysdate) from dual)  to see if could return a date but it just returns 'Not Applicable' in Collections. I also have the metrics refreshing in Real Time.

So I was wondering when setting up new metrics, can you use a SQL statement or does it have to be a Function?