Zoom Button 
Click the Zoom button to open a detail form for the field associated with a zoom button or press F9 from a line in an entry grid. The detail form that opens allows you to view or edit existing details or add new details. You then click the F9 key to close the detail form.
When you're in a detail form that also has a Zoom button beside a field, you must press Shift + F9 to see another detail form specifically for that field; if you simply press F9 again, the first detail form closes. (This function is referred to as Detail Zoom; you again press Shift + F9 to close the second detail form.)