  This letter is a comment on an article by T.C. Halsey and M.H. Jensen in
Nature about using recurrence times as a reliable tool to estimate multifractal
dimensions of strange attractors. Our aim is to emphasize that in the recent
mathematical literature (not cited by these authors), there are positive as
well as negative results about the use of such techniques. Thus one may be
careful in using this tool in practical situations (experimental data).
