Inputs:
    LookBackPeriod(252);  // Number of trading days in the look-back period

Variables:
    MaxHighMinusOpen(0),    // Variable to store the maximum value of (High - Open)
    HighestHighFromOpen(0), // Highest value of High - Open over the look-back period
    CurrentOpen(0),         // Current day's open price
    LineValue(0),           // Value to plot as the horizontal line
    i(0),                  // Loop counter
    PlotStartTime(0930),   // Start time for plotting
    PlotEndTime(1600);     // End time for plotting

// Initialize values and calculate the highest high from open at the start of each trading day
If Date <> Date[1] Then Begin
    HighestHighFromOpen = -999999; // Initialize for a new day

    // Loop through the look-back period to find the maximum value of (High - Open)
    For i = 0 To LookBackPeriod - 1 Begin
        MaxHighMinusOpen = HighD(i) - OpenD(i);
        If MaxHighMinusOpen > HighestHighFromOpen Then
            HighestHighFromOpen = MaxHighMinusOpen;
    End;

    // Calculate the value to plot as the horizontal line
    CurrentOpen = Open;
    LineValue = CurrentOpen + HighestHighFromOpen;
End;

// Plot the line during trading hours only
If Time >= PlotStartTime And Time <= PlotEndTime Then Begin
    Plot1(LineValue, "52 Extreme High from Open");
End
Else Begin
    SetPlotColor(1, Transparent); // Hide the line outside trading hours
End;