The following constants are used with the MsgBox function to identify what buttons and icons appear on a message box, and which button is the default. In addition, the modality of the MsgBox can be specified. 0 Display OK button only. Yes , No , and Cancel buttons.
First button is the default.
The user must respond to the message box before continuing work in the current application. All applications are suspended until the user responds to the message box. The following constants are used with the MsgBox function to identify which button a user has selected. Yes button was pressed. No button was pressed.