An x in the M (Modify) column means you can change the property. When (exp) is included in the description, you can specify a DataWindow expression as the value for that property.
Properties for Oval, Rectangle, and RoundRectangle controls in DataWindow objects also apply to RoundRectangle controls.
Property  | 
M  | 
Description  | 
|---|---|---|
x  | 
(exp) The radius of the vertical part of the rounded corner.  | 
|
x  | 
(exp) The radius of the horizontal part of the rounded corner.  |