Type Alias RowBound 

pub type RowBound = Vec<(ColId, Bound)>;

A scan-start key: each index-sort column pinned to a Bound. Empty / absent columns are treated as Min (a safety default — a real seek pins every sort column). Index-addressed; a small Vec, not a map (04 §4.3).

Aliased Type

pub struct RowBound { /* private fields */ }