Cursor Variables - Impementing Variant Records

The power of cursor variables comes from their ability to point to different cursors.
This test example comes from this doc

denis@TEST10G>
denis@TEST10G> create table emp_tab
  2  as
  3  select
  4    rownum empno,
  5    object_name ename,
  6    mod(rownum, 10) + 1 deptno ,
  7    rownum * 100 sal
  8  from all_objects
  9  where rownum < 100;

Table created.

denis@TEST10G>
denis@TEST10G>
denis@TEST10G> drop table dept_tab purge;

Table dropped.

denis@TEST10G> create table dept_tab
  2  as
  3  select
  4    rownum deptno,
  5    'd_' || rownum  deptname
  6  from all_objects
  7  where rownum <=10;

Table created.

denis@TEST10G>
denis@TEST10G>
denis@TEST10G> -- In the following package example, a discriminant is used to
denis@TEST10G> -- open a cursor variable to point to one of two different cursors:
denis@TEST10G>
denis@TEST10G> create or replace package emp_dept_data as
  2    type cv_type is ref cursor;
  3    procedure open_cv(cv     in out cv_type,
  4                      discrim  in positive);
  5  end emp_dept_data;
  6  /

Package created.

denis@TEST10G>
denis@TEST10G> create or replace package body emp_dept_data as
  2    procedure open_cv (cv in out cv_type,
  3                       discrim in positive) is
  4    begin
  5      if discrim = 1 then
  6         open cv for select * from emp_tab where sal > 2000;
  7      elsif discrim = 2 then
  8         open cv for select * from dept_tab;
  9      end if;
 10    end open_cv;
 11  end emp_dept_data;
 12  /

Package body created.

denis@TEST10G>
denis@TEST10G> -- You can call the open_cv procedure to open the cursor variable
denis@TEST10G> -- and point it to either a query on the emp_tab table or
denis@TEST10G> -- the dept_tab table.
denis@TEST10G>
denis@TEST10G> declare
  2    emp_rec emp_tab%rowtype;
  3    dept_rec dept_tab%rowtype;
  4    cv       emp_dept_data.cv_type;
  5
  6  begin
  7  --  emp_dept_data.open_cv(cv,2); -- open cv for emp_tab fetch
  8    emp_dept_data.open_cv(cv,1); -- open cv for emp_tab fetch
  9    fetch cv into dept_rec;   -- but fetch inot dept_tab record
 10                              -- which raises rowtype_mismatch
 11    dbms_output.put(dept_rec.deptno);
 12    dbms_output.put_line('  ' || dept_rec.deptname);
 13  exception
 14    when rowtype_mismatch then
 15      begin
 16        dbms_output.put_line
 17              ('Row type mismatch, fetching emp_tab data ...');
 18        fetch cv into emp_rec;
 19        dbms_output.put(emp_rec.deptno);
 20        dbms_output.put_line('  ' || emp_rec.ename);
 21      end;
 22  end;
 23  /
Row type mismatch, fetching emp_tab data ...
2  C_TS#

PL/SQL procedure successfully completed.