10.13. The amount that an operator is required to include in computing its annual earnings from a mine for a fiscal year, under subparagraph e of subparagraph 1 of the fourth paragraph of section 8, and in computing the mine-mouth output value in respect of the mine it operates, for the fiscal year, under subparagraph e of subparagraph 1 of the second paragraph of section 8.1.1, in respect of class 3A property or class 4A property, is equal to the amount by which the aggregate of the amounts referred to in subparagraphs a to h of paragraph 2 of the definition of “undepreciated capital cost” in the first paragraph of section 9, in respect of that class, exceeds the aggregate of the amounts referred to in subparagraphs a to d of paragraph 1 of the definition of that expression, up to the portion of that excess amount that is reasonably attributable to the operation of the mine.