text: --
  --     Find gaps.
  --
  --     This script finds "Value Gaps" in columns that contain
  --     numeric, non fractional values (integers), possibly 
  --     created by sequences.
  --
  select a+1        "From/Start Value", 
         lead_      "To (Value)",
         lead_ - a  "Size"
    from (
  select &&column                                            a,
         lag (&&column) over (order by &&column) lag_,
         lead(&&column) over (order by &&column) lead_,
         &&column - lead(&&column) over (order by &&column) count_
    from &&table
   order by &&column - lead(&&column) over (order by &&column)
  )
  where rownum < 20;
  