The 'default' property

Character vector (or integer scalar for the MsgBox class)

Valid for: OpenFile, SaveFile, MsgBox

Under Windows and Linux, for the SaveFile and OpenFile pre-defined dialogs, the default property determines the default file extension which will be added if the user specifies a file name without a file extension, for example 'txt'. File extensions must not exceed three characters, and the leading period should be omitted. It is ignored under MacOS.

For the MsgBox pre-defined dialog, the default property is an integer in the range 1 to 4, representing the default button which will be selected if the user presses the Enter key.