SCOTT@orcl_11g> CREATE Table your_table
  2    (col1  VARCHAR2(10),
  3  	col2  VARCHAR2(10),
  4  	col3  VARCHAR2(10))
  5  /

Table created.

SCOTT@orcl_11g> BEGIN
  2    INSERT INTO your_table VALUES ('test1 test', NULL, NULL);
  3    INSERT INTO your_table VALUES (NULL, 'test2 test', NULL);
  4    INSERT INTO your_table VALUES (NULL, NULL, 'test3 test');
  5  END;
  6  /

PL/SQL procedure successfully completed.

SCOTT@orcl_11g> BEGIN
  2    CTX_DDL.CREATE_PREFERENCE ('your_datastore', 'MULTI_COLUMN_DATASTORE');
  3    CTX_DDL.SET_ATTRIBUTE ('your_datastore', 'COLUMNS', 'col1, col2, col3');
  4    CTX_DDL.CREATE_SECTION_GROUP ('your_sec_group', 'BASIC_SECTION_GROUP');
  5    CTX_DDL.ADD_FIELD_SECTION ('your_sec_group', 'column1', 'col1', TRUE);
  6    CTX_DDL.ADD_FIELD_SECTION ('your_sec_group', 'column2', 'col2', TRUE);
  7    CTX_DDL.ADD_FIELD_SECTION ('your_sec_group', 'column3', 'col3', TRUE);
  8  END;
  9  /

PL/SQL procedure successfully completed.

SCOTT@orcl_11g> CREATE INDEX your_index ON your_table (col1)
  2  INDEXTYPE IS CTXSYS.CONTEXT
  3  PARAMETERS
  4    ('DATASTORE	your_datastore
  5  	 SECTION GROUP	your_sec_group
  6  	 STOPLIST	CTXSYS.EMPTY_STOPLIST')
  7  /

Index created.

SCOTT@orcl_11g> CREATE OR REPLACE FUNCTION list_element
  2  	(p_string    VARCHAR2,
  3  	 p_element   INTEGER,
  4  	 p_separator VARCHAR2 DEFAULT ':')
  5  	RETURN	     VARCHAR2
  6  AS
  7    v_string      VARCHAR2 (32767);
  8  BEGIN
  9    v_string := p_string || p_separator;
 10    FOR i IN 1 .. p_element - 1 LOOP
 11  	 v_string := SUBSTR (v_string,
 12  			     INSTR (v_string, p_separator)
 13  			       + LENGTH (p_separator));
 14    END LOOP;
 15    RETURN SUBSTR (v_string, 1, INSTR (v_string, p_separator) - 1);
 16  END list_element;
 17  /

Function created.

SCOTT@orcl_11g> SELECT t.*, ROWID FROM your_table t
  2  /

COL1       COL2       COL3       ROWID
---------- ---------- ---------- ------------------
test1 test                       AAAYHcAAEAAAyoYAAA
           test2 test            AAAYHcAAEAAAyoYAAB
                      test3 test AAAYHcAAEAAAyoYAAC

SCOTT@orcl_11g> COLUMN token_text FORMAT A15
SCOTT@orcl_11g> COLUMN token_type FORMAT 9999999999
SCOTT@orcl_11g> SELECT token_text, token_type, token_first, token_last
  2  FROM   dr$your_index$i
  3  /

TOKEN_TEXT       TOKEN_TYPE TOKEN_FIRST TOKEN_LAST
--------------- ----------- ----------- ----------
TEST                      0           1          3
TEST                     16           1          1
TEST                     17           2          2
TEST                     18           3          3
TEST1                     0           1          1
TEST1                    16           1          1
TEST2                     0           2          2
TEST2                    17           2          2
TEST3                     0           3          3
TEST3                    18           3          3

10 rows selected.

SCOTT@orcl_11g> SELECT * FROM dr$your_index$k
  2  /

     DOCID TEXTKEY
---------- ------------------
         1 AAAYHcAAEAAAyoYAAA
         2 AAAYHcAAEAAAyoYAAB
         3 AAAYHcAAEAAAyoYAAC

SCOTT@orcl_11g> COLUMN ixv_value FORMAT A20
SCOTT@orcl_11g> COLUMN from_column FORMAT A15
SCOTT@orcl_11g> SELECT ixv_value,
  2  	    list_element (ixv_value, 2) AS from_column,
  3  	    TO_NUMBER (list_element (ixv_value, 3 )) AS token_type
  4  FROM   ctx_user_index_values
  5  WHERE  ixv_index_name = 'YOUR_INDEX'
  6  AND    ixv_class = 'SECTION_GROUP'
  7  /

IXV_VALUE            FROM_COLUMN      TOKEN_TYPE
-------------------- --------------- -----------
COLUMN3:COL3:18:Y    COL3                     18
COLUMN1:COL1:16:Y    COL1                     16
COLUMN2:COL2:17:Y    COL2                     17

SCOTT@orcl_11g> SELECT t.*,
  2  	    i.token_text,
  3  	    list_element (v.ixv_value, 2) AS from_column
  4  FROM   your_table t, dr$your_index$i i, dr$your_index$k k, ctx_user_index_values v
  5  WHERE  CONTAINS (t.col1, 'test1 OR test2 OR test3') > 0
  6  AND    i.token_type = TO_NUMBER (list_element (v.ixv_value, 3))
  7  AND    k.docid BETWEEN i.token_first AND i.token_last
  8  AND    k.textkey = t.ROWID
  9  /

COL1       COL2       COL3       TOKEN_TEXT      FROM_COLUMN
---------- ---------- ---------- --------------- ---------------
                      test3 test TEST3           COL3
                      test3 test TEST            COL3
           test2 test            TEST2           COL2
           test2 test            TEST            COL2
test1 test                       TEST1           COL1
test1 test                       TEST            COL1

6 rows selected.

SCOTT@orcl_11g> SELECT t.*,
  2  	    i.token_text,
  3  	    list_element (v.ixv_value, 2) AS from_column
  4  FROM   your_table t, dr$your_index$i i, dr$your_index$k k, ctx_user_index_values v
  5  WHERE  CONTAINS (t.col1, 'test2') > 0
  6  AND    i.token_text = 'TEST2'
  7  AND    i.token_type = TO_NUMBER (list_element (v.ixv_value, 3))
  8  AND    k.docid BETWEEN i.token_first AND i.token_last
  9  AND    k.textkey = t.ROWID
 10  /

COL1       COL2       COL3       TOKEN_TEXT      FROM_COLUMN
---------- ---------- ---------- --------------- ---------------
           test2 test            TEST2           COL2

SCOTT@orcl_11g> 

SCOTT@orcl> -- Supposing that you have tables and data like this:
SCOTT@orcl> CREATE TABLE master
  2    (id	NUMBER PRIMARY KEY,
  3  	animal	VARCHAR2(30),
  4  	dummy	VARCHAR2(1))
  5  /

Table created.

SCOTT@orcl> INSERT ALL
  2  INTO master VALUES (1, 'test test1', NULL)
  3  INTO master VALUES (2, 'test test3', NULL)
  4  SELECT * FROM DUAL
  5  /

2 rows created.

SCOTT@orcl> CREATE TABLE detail
  2    (id	NUMBER REFERENCES master (id),
  3  	name	VARCHAR2(30))
  4  /

Table created.

SCOTT@orcl> INSERT ALL
  2  INTO detail VALUES (1, 'test test2')
  3  INTO detail VALUES (2, 'test4')
  4  SELECT * FROM DUAL
  5  /

2 rows created.

SCOTT@orcl> -- and you have a procedure like this:
SCOTT@orcl> CREATE OR REPLACE PROCEDURE test_proc
  2    (p_rowid IN	      ROWID,
  3  	p_clob	IN OUT NOCOPY CLOB)
  4  AS
  5  BEGIN
  6    FOR r1 IN
  7  	 (SELECT * FROM master WHERE ROWID = p_rowid)
  8    LOOP
  9  	 DBMS_LOB.WRITEAPPEND (p_clob, 8, '<animal>');
 10  	 DBMS_LOB.WRITEAPPEND (p_clob, LENGTH (r1.animal), r1.animal);
 11  	 DBMS_LOB.WRITEAPPEND (p_clob, 9, '</animal>');
 12  	 FOR r2 IN
 13  	   (SELECT * FROM detail WHERE id = r1.id)
 14  	 LOOP
 15  	   DBMS_LOB.WRITEAPPEND (p_clob, 6, '<name>');
 16  	   DBMS_LOB.WRITEAPPEND (p_clob, LENGTH (r2.name), r2.name);
 17  	   DBMS_LOB.WRITEAPPEND (p_clob, 7, '</name>');
 18  	 END LOOP;
 19    END LOOP;
 20  END test_proc;
 21  /

Procedure created.

SCOTT@orcl> SHOW ERRORS
No errors.
SCOTT@orcl> -- that produces xml clobs like this:
SCOTT@orcl> DECLARE
  2    v_clob  CLOB;
  3  BEGIN
  4    FOR r1 IN
  5  	 (SELECT ROWID FROM master)
  6    LOOP
  7  	 DBMS_LOB.CREATETEMPORARY (v_clob, FALSE);
  8  	 test_proc (r1.ROWID, v_clob);
  9  	 DBMS_OUTPUT.PUT_LINE (v_clob);
 10  	 DBMS_LOB.FREETEMPORARY (v_clob);
 11    END LOOP;
 12  END;
 13  /
<animal>test test1</animal><name>test test2</name>
<animal>test test3</animal><name>test4</name>

PL/SQL procedure successfully completed.

SCOTT@orcl> -- and you have a user_datastore that uses that procedure like this:
SCOTT@orcl> BEGIN
  2    CTX_DDL.CREATE_PREFERENCE ('test_ds', 'USER_DATASTORE');
  3    CTX_DDL.SET_ATTRIBUTE ('test_ds', 'PROCEDURE', 'test_proc');
  4  END;
  5  /

PL/SQL procedure successfully completed.

SCOTT@orcl> -- and you have a text index that uses that datastore
SCOTT@orcl> -- and some kind of section group like this:
SCOTT@orcl> CREATE INDEX your_index ON master (dummy)
  2  INDEXTYPE IS CTXSYS.CONTEXT
  3  PARAMETERS
  4    ('DATASTORE	test_ds
  5  	 SECTION GROUP	CTXSYS.AUTO_SECTION_GROUP')
  6  /

Index created.

SCOTT@orcl> -- then you can get the values and categories accessing the index like this:
SCOTT@orcl> VARIABLE search_string VARCHAR2(30)
SCOTT@orcl> EXEC :search_string := 'test'

PL/SQL procedure successfully completed.

SCOTT@orcl> COLUMN "Value"    FORMAT A30
SCOTT@orcl> COLUMN "category" FORMAT A30
SCOTT@orcl> SET AUTOTRACE ON EXPLAIN
SCOTT@orcl> SELECT :search_string "Value",
  2  	    'animal'	   "category"
  3  FROM   master
  4  WHERE  CONTAINS (dummy, :search_string || ' WITHIN animal') > 0
  5  UNION
  6  SELECT :search_string "Value",
  7  	    'name'	   "category"
  8  FROM   master
  9  WHERE  CONTAINS (dummy, :search_string || ' WITHIN name') > 0
 10  /

Value                          category
------------------------------ ------------------------------
test                           animal
test                           name

2 rows selected.


Execution Plan
----------------------------------------------------------
Plan hash value: 1954242363

-------------------------------------------------------------------------------
| Id  | Operation        | Name       | Rows  | Bytes | Cost (%CPU)| Time     |
-------------------------------------------------------------------------------
|   0 | SELECT STATEMENT |            |     2 |    28 |    10  (60)| 00:00:01 |
|   1 |  SORT UNIQUE     |            |     2 |    28 |    10  (60)| 00:00:01 |
|   2 |   UNION-ALL      |            |       |       |            |          |
|*  3 |    DOMAIN INDEX  | YOUR_INDEX |     1 |    14 |     4   (0)| 00:00:01 |
|*  4 |    DOMAIN INDEX  | YOUR_INDEX |     1 |    14 |     4   (0)| 00:00:01 |
-------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

   3 - access("CTXSYS"."CONTAINS"("DUMMY",:SEARCH_STRING||' WITHIN
              animal')>0)
   4 - access("CTXSYS"."CONTAINS"("DUMMY",:SEARCH_STRING||' WITHIN
              name')>0)

Note
-----
   - dynamic sampling used for this statement (level=2)

SCOTT@orcl> EXEC :search_string := 'test2'

PL/SQL procedure successfully completed.

SCOTT@orcl> /

Value                          category
------------------------------ ------------------------------
test2                          name

1 row selected.


Execution Plan
----------------------------------------------------------
Plan hash value: 1954242363

-------------------------------------------------------------------------------
| Id  | Operation        | Name       | Rows  | Bytes | Cost (%CPU)| Time     |
-------------------------------------------------------------------------------
|   0 | SELECT STATEMENT |            |     2 |    28 |    10  (60)| 00:00:01 |
|   1 |  SORT UNIQUE     |            |     2 |    28 |    10  (60)| 00:00:01 |
|   2 |   UNION-ALL      |            |       |       |            |          |
|*  3 |    DOMAIN INDEX  | YOUR_INDEX |     1 |    14 |     4   (0)| 00:00:01 |
|*  4 |    DOMAIN INDEX  | YOUR_INDEX |     1 |    14 |     4   (0)| 00:00:01 |
-------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

   3 - access("CTXSYS"."CONTAINS"("DUMMY",:SEARCH_STRING||' WITHIN
              animal')>0)
   4 - access("CTXSYS"."CONTAINS"("DUMMY",:SEARCH_STRING||' WITHIN
              name')>0)

Note
-----
   - dynamic sampling used for this statement (level=2)

SCOTT@orcl>