From what I understand yes.can someone explain how this works? do you mean they could split half your adv with 1 unit of ext?
Each 'unit' is out of 50. Hence Advance is 2units (out of 100) and ext 1 is one unit (out of 50). Therefore they take one unit from each.
But that only occurs if your extension mark is greater than your advance mark, assuming you have more than 10 units.