; or (ii) upstream inputs for 1 or more categories of covered products. (E) Any other country that the Secretary determines to be appropriate, including any country that the Secretary determines is a significant producer or exporter of at least 1 category of covered products. (6) Covered product (A) In general The term covered product means a product covered by— (i) any of the headings or subheadings of the Harmonized Tariff Schedule of the United States described parenthetically in paragraph (4)(B); or (ii) any other heading or subheading of the Harmonized Tariff Schedule of the United States included within a category of covered products determined by the Secretary in accordance with paragraph (4)(A)(ii). (B) List of covered products The Secretary shall maintain a list of covered products that identifies the category of covered products associated with each covered product on the list. (7) Greenhouse gas The term greenhouse gas has the meaning given the term in section 901 of the Energy Independence and Security Act of 2007 ( 42 U.S.C. 17321 ). (8) Product emissions intensity (A) In general The term product emissions intensity means the quantity of greenhouse gases emitted to the atmosphere as a result of the extraction, production, processing, manufacture, and assembly, as applicable, of 1 unit of a covered product, including the greenhouse gas emissions of an upstream input that is incorporated into a downstream covered product. (B) Units of measurement The Secretary, as the Secretary determines to be appropriate, shall designate the units of measurement in which the product emissions intensity of a covered product shall be expressed, which may include— (i) metric tons of CO 2 -e per metric ton of a covered product; (ii) metric tons of CO 2 -e per dollar value of a covered product