I think, they are looking for something like this.

Nested Table as a storage mechanism, not in plsql.

demo@ORA12C> create or replace type myobj
  2  is object(x int,y varchar2(30));
  3  /

Type created.

demo@ORA12C>
demo@ORA12C> create or replace type mytab
  2  is table of myobj;
  3  /

Type created.

demo@ORA12C> create table t( owner varchar2(30),
  2             object_type varchar2(30),
  3             object_details mytab )
  4  nested table object_details store
  5  as object_details_ntt;

Table created.

demo@ORA12C> insert into t(owner,object_type,object_details)
  2  select owner,object_type, cast( collect(myobj(object_id,object_name)) as mytab)
  3  from all_objects
  4  group by owner,object_type;

159 rows created.

demo@ORA12C> commit;

Commit complete.

demo@ORA12C> create table t2
  2  nested table object_details
  3  store as object_details_ntt2
  4  as
  5  select * from t;

Table created.

demo@ORA12C> set linesize 71
demo@ORA12C> desc t2
 Name                                Null?    Type
 ----------------------------------- -------- -------------------------
 OWNER                                        VARCHAR2(30)
 OBJECT_TYPE                                  VARCHAR2(30)
 OBJECT_DETAILS                               MYTAB

demo@ORA12C> select count(*) from t2;

  COUNT(*)
----------
       159

1 row selected.

demo@ORA12C>

Thanks very much . I have another followup question , have been trying all day for a solution without success, appreciate if i could get some help.

I have nested table like below which is already loaded.

create or replace TYPE access_t AS OBJECT (
   AccessID        VARCHAR2(50),
   Eligibility       char(1)
   );
/

create or replace TYPE Access_tab IS TABLE OF access_t;
/

create or replace TYPE add_t AS OBJECT (
   city    VARCHAR2(100),
   state   VARCHAR2(100),
   zip     VARCHAR2(10),
   APOINTSARRAY Access_tab )
;
/

create or replace TYPE add_tab IS TABLE OF add_t;
/

CREATE TABLE RQST_STATUS
   (    RQST_ID NUMBER, 
        ADDRESS add_tab
   ) 
 NESTED TABLE ADDRESS STORE AS RQST_STATUS_ADDRESS
 ( NESTED TABLE APOINTSARRAY STORE AS RQST_STATUS_AP)
;

Now without changing TYPE add_t (since its used in other tables which do not need this change) , i need to add 2 additional columns to ADDRESS.
I took backup of the table , altered the table to add another new field.

create or replace TYPE add_t_new AS OBJECT (
   city    VARCHAR2(100),
   state   VARCHAR2(100),
   zip     VARCHAR2(10),
   APOINTSARRAY Access_tab,
   Latitude      VARCHAR2(10),
   Longitude     VARCHAR2(10),
)
;
/

create or replace TYPE add_tab_new IS TABLE OF add_t_new;
/

CREATE TABLE RQST_STATUS
   (    RQST_ID NUMBER, 
        ADDRESS add_tab
   ) 
 NESTED TABLE ADDRESS STORE AS RQST_STATUS_ADDRESS
 ( NESTED TABLE APOINTSARRAY STORE AS RQST_STATUS_AP)
;

ALTER TABLE RQST_STATUS ADD 
(
    ADDRESS_NEW   add_tab_new
) 
NESTED TABLE ADDRESS_NEW STORE AS ADDRESS_NEW_V1
  (NESTED TABLE APOINTSARRAY STORE AS APOINTSARRAY_V1) ;

So now , i have old and new fields in the same table. 
How can i now insert data from old field to new field ? with null values for the 2 additional fields.

I intend to drop the old column and then rename the new column to old after.
Thanks.

I had the same question as the OP. Jeyabal's response was succinct and complete.