      \fitem{map_history_date}(\emph{variable}) : This is a special
      form. It returns a map of the date in physical time of the updates
      of the variable in argument. See. sect.~\ref{sec:mapvariable}
      page~\pageref{sec:mapvariable} and the 
      \code{@tab_historyXXX} functions. 


      %%% -------------------------------------------------------

