this doesn't offer an opinion on tails vs body gap fills butttt there is some good general info here. <A HREF="http://stockcharts.com/school/doku.php?id=chart_school:chart_analysis:gaps_and_gap_analysi" target="_blank">http://stockcharts.com/school/doku.php?id=chart_school:chart_analysis:gaps_and_gap_analysi</A>