Function name_range 

pub fn name_range(
    doc: &mut AutoCommit,
    start: &HistoryEntryId,
    end: Option<&HistoryEntryId>,
    label: &str,
) -> String

Names the run of changes from start to end, or opens an unbounded run when end is None. Returns the record id (also the document key). The transaction is left open — the host commits, so the naming lands stamped and attributed like any other edit.