(2) Method of computing deduction For purposes of paragraph (1)— (A) The term “estate tax” means the tax imposed on the estate of the decedent or any prior decedent under section 2001 or 2101, reduced by the credits against such tax. (B) The net value for estate tax purposes of all the items described in subsection (a)(1) shall be the excess of the value for estate tax purposes of all the items described in subsection (a)(1) over the deductions from the gross estate in respect of claims which represent the deductions and credit described in subsection (b). Such net value shall be determined with respect to the provisions of section 421(c)(2), relating to the deduction for estate tax with respect to stock options to which part II of subchapter D applies. (C) The estate tax attributable to such net value shall be an amount equal to the excess of the estate tax over the estate tax computed without including in the gross estate such net value.
26 USC § 691(c)(2)
None identified, default scope is assumed to be the parent (part II) of this section.