protected void Page_Load(object sender, EventArgs e) {
        if (!IsPostBack) {
            populate();
        }
        populateVolatile();
    }

        // add each type/num info to table
        foreach (TypeNumInfo tni in volInfo.typeNumRows) {
            TableRow tr = new TableRow();
 
            // index number
            TableCell tc1 = new TableCell();
            tc1.Text = tni.idx.ToString();
            tr.Cells.Add(tc1);
 
            // add a DDL
            TableCell tc2 = new TableCell();
            DropDownList ddl = new DropDownList();
 
            // add ID and list data
            ddl.ID = "ddl" + tni.idx;
            foreach (ListItem li in dTypes) {
                ddl.Items.Add(li);
            }
 
            // set the selected
            // TODO not working
            ddl.SelectedIndex = tni.typeSel;
 
            tc2.Controls.Add(ddl);
            tr.Cells.Add(tc2);
 
            tblTypeNum.Rows.Add(tr);
        }

    protected void bAddTypeNum_Click(object sender, EventArgs e) {
        // get dept, applies selections from static controls
        statInfo.selDept = ddlDept.SelectedIndex;
        statInfo.selApplies = ddlApplies.SelectedIndex;
 
        // create new type/num info representing tablerow data
        TypeNumInfo tni = new TypeNumInfo();
        int lastIdx = volInfo.typeNumRows.Count;
        tni.idx = lastIdx + 1;
 
        // add to list
        volInfo.typeNumRows.Add(tni);
 
        // cache previous rows
        int i = 0;
        foreach (TableRow tr in tblTypeNum.Rows) {
            // if row has droplist, i.e. more than 1 cell
            if (tr.Cells.Count > 1) {
                DropDownList ddl = (DropDownList)tr.Cells[1].Controls[0];
 
                // get the selection in that row
                // TODO not working reliably
                volInfo.typeNumRows[i++].typeSel = ddl.SelectedIndex;
            }
        }
 
        // update session
        Session[strStat] = statInfo;
        Session[strVol] = volInfo;
 
        // draw as new page
        Response.Redirect("");
    }