private void cbLLPrefix_SelectedValueChanged( object sender, EventArgs e )
{
if (edtLLValue.Quantity == null)
edtLLValue.Quantity = new Quantity();
if (edtLLValue.Quantity.Unit == null)
edtLLValue.Quantity.Unit = new StandardUnit();
edtLLValue.Quantity.Unit.Prefix = cbLLPrefix.SelectedValue as string;
if (_errorLimit != null)
edtErrorLimit.Text = _errorLimit.ToString();
}