This indicator can only be used for Range Charts with MultiCharts.
It indicates the possible location of the close of the current bar, and the open of the next. Either in case of up move or down move. So it draws 4 lines all together.
Let's take the example of a 8-range chart (8-point in MultiCharts' terminology).
Let L and H be the current Low and the current High of the bar under formation.
If the price moves up and reaches L + 9 ticks, the current bar will be closed at L + 8 ticks, and the next bar will open at L + 9 ticks.
If the price moves down and reaches H - 9 ticks, the current bar will be closed at H - 8 ticks, and the next bar will open at H - 9 ticks.
So, when a bar is under formation, the indicator draws 2 little dotted lines above the bar, at L+8 and L+9, as well as 2 little dotted lines below the bar, at H-8 and H-9. They correspond to the possible levels of the close of the current bar, and the open of the next, either in the case of an up move, or in the case of a down move:
It has to be underlined that, by definition of a range chart, these positions are not final. If the current H or the current L of the bar under formation moves, the dotted lines will move also.
However, as soon as current H-L of the current bar equals 8 ticks, we know for sure the position of the 4 above-mentioned open and close, and the line becomes solid: