

   TTiimmee WWiinnddoowwss

        window(x, start, end)

   AArrgguummeennttss::

          x: a time-series or other object.

      start: the start time of the period of interest.

        end: the end time of the period of interest.

   DDeessccrriippttiioonn::

        `window' is a generic function which extracts the sub-
        set of the object `x' observed between the times
        `start' and `end'.  Methods are available for time
        series and point-processes.

   SSeeee AAllssoo::

        `time', `ts'.

   EExxaammpplleess::

        data(presidents)
        sixties <- window(presidents, 1960, c(1969,4))

