Display methods on Form Datasource

See http://msdn.microsoft.com/en-us/library/aa595058.aspx

To create a display method, place the display keyword immediately in front of the method’s return type. For example:

display Amount amount()

display methods must have a return type. The return value is typically a calculated value (for example, a sum). For an example, see How to: Create Form Controls.

There should no parameters in a display method unless it is on a form data source where you must include the data source as a parameter.
For example:

display InventQty accumulated(InventBudgetInvent Budget)

Note

You must use display on a form data source method when the return value is to be shown on a grid control.