public void SetAdditionalOperand(int index, Operand operand)
{
CheckAddition();
//if (addition.AdditionalOperands == null) addition.AdditionalOperands = new Operand[253];
//Debug.Assert(index < 255, @"No Index");
Debug.Assert(index >= 3, @"No Index");
SizeAdditionalOperands(index - 3);
addition.AdditionalOperands[index - 3] = operand;
}