property specifies that the corresponding button will be operated when you press the Return key. If you open the dialogue box or form and do not carry out any further action, the button with this property is the default button.
属性用于指定按 Return 键时将启动的按钮。如果打开对话框或窗体且不执行任何其他操作，则具有此属性的按钮为默认按钮。