B&G Deckman - Manual (Page 149)

Chapter 10: Wind and current forecasts
9.22
By clicking on the link tab at the top of the Edit GRIBs window, you
can make Deckman's interpolation of the forecasts more accurate. What
you do here is to link a weather feature at two different forecast times by
moving each end of the red line (shown heavy black in Figure 9.16),
making it easier for Deckman to interpolate for any time in between. In
the example, a link has been placed between the centre of the low
pressure system on each forecast map, thus telling Deckman something
of the expected movement.