with
v_data as
( select 20  as beg, 300 as en, 'VI' as k from dual
  union all
  select 400 as beg, 450 as en, 'IV' as k from dual
  union all
  select 700 as beg, 720 as en, 'V' as k from dual
),
s_data as
( select 0 as beg, 1300 as en, 'S0' as k  from dual  union all
  select 1300 as beg, 2300 as en, 'S1' as k  from dual
  )

with
v_data as
( select 20  as beg, 300 as en, 'V' as k from dual
  union all
  select 400 as beg, 450 as en, 'V' as k from dual
  union all
  select 700 as beg, 720 as en, 'V' as k from dual
),
s_data as
( select 0 as beg, 2300 as en, 'S' as k  from dual
  ),
interleave as
( select beg_int, end_int
    from
    ( select point as beg_int, lead(point) over (order by point) as end_int
        from
        ( select beg as point from v_data
          union
          select en as point from v_data
          union
          select beg as point from s_data
          union
          select en as point from s_data
        )
    )
    where end_int is not null
)
select beg_int, end_int, v.k as v_k
        , s.k as s_k
from interleave i
left join v_data v 
    on ( beg_int >= v.beg and end_int <= v.en)
left join s_data s 
    on ( beg_int >= s.beg and end_int <= s.en);