Parameter is the table and field name that you want to sum in the form of TableName.FieldName. The specified Table must be a Child of the calling Record.
Description:
The Parameter may also include a trailing IF statement that will be used to test if the item found qualifies. Multiple "AND" criteria may be separated with the & symbol.
Example:
[+] Finance.Item.Amount
[+] Finance.Item.Amount IF Status = "Completed"