[typo]
What most people do for PVS is
> Within the full-window search,
> • successors of expected-Cut nodes are expected-All nodes
> • successors of expected-All nodes are expected-Cut nodes
> • the first successor of an expected-PV node is an expected-PV node and the
>   remaining successors are expected-Cut (unless a zero-window search of that
>   successor fails, in which case the successor is expected-PV).
Note that this implies that when the first successor of an expected-PV node
fails to meet alpha, the node becomes expected-All.

The root of a zero-window search is always expected-Cut, and so there are no
expected-PV nodes within a zero-window search tree.