This subsection shall apply only if, by such transfer, such power in the donee spouse to appoint the interest, or such portion, whether exercisable by will or during life, is exercisable by such spouse alone and in all events. For purposes of this subsection, the term “specific portion” only includes a portion determined on a fractional or percentage basis.
26 USC § 2523(e)
None identified. Default scope is assumed to be the entire title.