According to R-lang.pdf (Section 2): Function mode gives information about the mode of an object in the sense of Becker, Chambers & Wilks (1988), and is more compatible with other implementations of the S language. Finally, the function storage.mode returns the storage mode of its argument in the sense of Becker et al. (1988). Could somebody give an explanation, without the reference to S (as the user may not know R enough, let along S), on why there are the three functions typeof(), mode() and storage.mode(), how and when to use them, what are the implication of these functions? The above explanation on mode and storage.mode says nothing except pointing the reader to two other old papers. Could somebody improve the document so that users without S background can still understand them?