Zoom Button 
or 
The Zoom button and the F9 key let you view or enter supplementary information for a transaction detail or for a field.
In any detail entry grid, you can select a detail line, then click the F9 button to open a form that displays all the fields for a single detail, including additional tax-related fields that don't appear on the detail entry grid. You can edit existing details, and even add new details for the document.
Beside any field that displays a Zoom button, you can click the button, or press the F9 key while the insertion point is in the field, to open a form that lets you view and enter supplementary information specific to that field. In a detail entry grid, you press the Shift + F9 keys while the insertion point is in the field.