using System;

using System.Linq;

​

public class Program

{

    public static void Main()

    {

        string file = "1;1.5;BK;200;PAN5A;PAN5B;ABC\r\n2;0.75;BK;620;PAN3A;PAN3A;ACC\r\n3;2;RD;150;PAN2A;PAN2A;AAA\r\n4;1.5;BL;500;PAN2A;PAN2A;ABB\r\n5;0.75;GY;250;PAN1A;PAN2A;AAA\r\n6;5.25;GY;200;PAN3A;PAN3B;CCC\r\n7;1.25;BU;150;PAN4A;PAN4A;DDD\r\n8;0.75;BK;800;PAN4A;PAN4A;BBB";

        string[] lines = file.Split(new string[]{"\r\n"}, StringSplitOptions.RemoveEmptyEntries);

        var sorted = lines.Select(line => new

        {

        SortKeyColor = line.Split(';')[2], SortKeySection = double.Parse(line.Split(';')[1], CultureInfo.InvariantCulture), SortKeyLenght = int.Parse(line.Split(';')[3]), Line = line

        }

​

        ).OrderBy(x => x.SortKeyColor, new ColorNameComparer()).ThenBy(x => x.SortKeySection).ThenBy(x => x.SortKeyLenght).Select(x => x.Line);

        foreach (var entry in sorted)

            Console.WriteLine(entry);

    }

}

​

public class ColorNameComparer : IComparer<string>

{

    private readonly List<string> colorOrder = new List<string>{"GY", "BL", "RD"};

    public int Compare(string x, string y)

    {

        if (x == y)

            return 0;

        if (x == "BK")

            return 1;

        if (y == "BK")

            return -1;

        if (colorOrder.Contains(x) && colorOrder.Contains(y))

            return colorOrder.IndexOf(x) > colorOrder.IndexOf(y) ? 1 : -1;

        if (colorOrder.Contains(x))

            return -1;

        if (colorOrder.Contains(y))

            return 1;

        return String.Compare(x, y, StringComparison.Ordinal);

    }

}