It's a place holder. See http://en.wikipedia.org/wiki/Foo HTH KJ "Simon Tian" <simon.yt at gmail.com> wrote in message news:2119d1440908012150j373bfaf5v9d498bded94fff1 at mail.gmail.com... > Hi R users, > > I really want to know what exactly ".[foo]" means. > > Thanks in advance. -Simon > > [[alternative HTML version deleted]] >