CREATE TYPE TEST_103 AS  OBJECT(CHILD_CSE_ID VARCHAR2(25));
CREATE TYPE TEST_104 AS TABLE OF TEST_103;

CREATE TABLE TEST_105 (
  CL_ID     VARCHAR2(25),
  CSE_ID    VARCHAR2(14),
  EXP_ID    VARCHAR2(13),
  CS_LST    TEST_104
)NESTED TABLE CS_LST STORE AS TEST_104_TAB;

INSERT INTO TEST_105 values ('A','100','E_100',TEST_104(TEST_103('C_100'),TEST_103('C_105')));
INSERT INTO TEST_105 values ('A','200','E_200',TEST_104(TEST_103('C_200'),TEST_103('C_205')));
INSERT INTO TEST_105 values ('A','300','E_300',TEST_104(TEST_103('C_300'),TEST_103('C_305')));
INSERT INTO TEST_105 values ('A','300',NULL,NULL);
INSERT INTO TEST_105 values ('B','400','E_400',TEST_104(TEST_103('C_400'),TEST_103('C_405')));
INSERT INTO TEST_105 values ('B','500','E_500',TEST_104(TEST_103('C_500'),TEST_103('C_505')));
INSERT INTO TEST_105 values ('B','600','E_600',TEST_104(TEST_103('C_600'),TEST_103('C_605'),TEST_103('C_606')));
COMMIT ;

SELECT * FROM TEST_105;

<?xml version="1.0" encoding="UTF-8"?>
 <Main_case>
    <cl_id="A">
       <cse_id="100">
          <cs_lst>
            <case>C_100</case>
            <case>C_105</case>
          </cs_lst>
       </cse_id>
       <cse_id="200">
          <cs_lst>
            <case>C_200</case>
            <case>C_205</case>
          </cs_lst>
       </cse_id>
       <cse_id="300">
          <cs_lst>
            <case>C_300</case>
            <case>C_305</case>
          </cs_lst>
       </cse_id>
     </cl_id>

    <cl_id="B">
       <cse_id="400">
          <cs_lst>
            <case>C_400</case>
            <case>C_405</case>
          </cs_lst>
       </cse_id>
       <cse_id="500">
          <cs_lst>
            <case>C_500</case>
            <case>C_505</case>
          </cs_lst>
       </cse_id>
       <cse_id="300">
          <cs_lst>
            <case>C_600</case>
            <case>C_605</case>
            <case>C_606</case>
          </cs_lst>
       </cse_id>
     </cl_id>
 </Main_case>