As far I understand from your question, you may need to use Two
Dimensional Array or may be Multidimensional array according to the
requirements:
Here is a Raw example which might be helpful to you:

using System;

class TwoD {
 public static void Main() {
   int t, i;
   int[,] table = new int[6, 3]; //Declaring the array
/* This is the array named "table" of 6 Rows and 3 Columns/Fields i.e.
for each row there are 3 columns/fields. You can increase the number
of rows according to your data size.

for each row there would be a combination of 3 columns.
*/

// Data for Row 1
table[0,0]=1;
table[0,1]=1;
table[0,2]=1

// Data for Row 2
table[1,0]=2;
table[1,1]=1;
table[1,2]=1

// Data for Row 3
table[2,0]=2;
table[2,1]=1;
table[2,2]=2

// go on up to 5
table[5,0]=5;
table[5,1]=1;
table[5,2]=3

   }
 }
}

Here is an illustration for this:

                          Columns
        thID  |  dthID |  locID
Rows-------------------------------------------
R1        1    |    1    |   1
R2        2    |    1    |   1
R3        2    |    1    |   2
R4        2    |    2    |   2
R5        2    |    4    |   2
R6        3    |    4    |   3

You can use some Loop statement like "for" to access the combinations
Hope this helps.

Stainless,
An ArrayList holds type Object, there is nothing to define.
If you don't know how many elements each of your "objects" will have, you
can even store individual ArrayList instances in each main ArrayList element.

Peter

Not entirely clear what you are trying to do - is it something like:

class RowKey
{
    int thID;
    int dthID;
    int locID;

    void RowKey(th, dth, loc)
    {
        thID = th;
        dthID = dth;
        locID = loc;
    }
}

ArrayList list = new ArrayList();
list.Add(new RowKey(1,1,1));
list.Add(new RowKey(2,1,1));, etc. ??

You could then use constructs like:
foreach (RowKey rk in list) { . . . } or RowKey rk = (RowKey)list[i], etc.

If this is what you are after (more or less), then you could look into
List<RowKey> (the generic).  Also, if you want to preserve the order by sorting
your list you may want to implement IComparable on the RowKey class . . .

HTH,
-rick-