'Declaration

Public Property readonly As Boolean

public bool readonly { get; set; }

public: __property bool get_readonly();
public: __property void set_readonly(
   bool value
);

public:
property bool readonly {
   bool get();
   void set(bool value);
}

True - the user may NOT change the value of the field; any associated widget annotations will not interact with the user, i.e. they will not respond to mouse clicks or change their appearance in response to mouse motions.
false - the user may change the value of the field.