System Tables Views Oracle PLSQL

SQL>
SQL> select table_name, tablespace_name
  2        from user_tables where rownum < 50
  3       order by table_name;
TABLE_NAME                     TABLESPACE_NAME
------------------------------ ------------------------------
ARGUMENT$                      SYSTEM
ATTRCOL$                       SYSTEM
BOOTSTRAP$                     SYSTEM
CCOL$                          SYSTEM
CDEF$                          SYSTEM
CLU$                           SYSTEM
COL$                           SYSTEM
COLTYPE$                       SYSTEM
CON$                           SYSTEM
DIR$                           SYSTEM
ERROR$                         SYSTEM
TABLE_NAME                     TABLESPACE_NAME
------------------------------ ------------------------------
FET$                           SYSTEM
FILE$                          SYSTEM
ICOL$                          SYSTEM
ICOLDEP$                       SYSTEM
IDL_CHAR$                      SYSTEM
IDL_SB4$                       SYSTEM
IDL_UB1$                       SYSTEM
IDL_UB2$                       SYSTEM
IND$                           SYSTEM
JAVAOBJ$                       SYSTEM
LIBRARY$                       SYSTEM
TABLE_NAME                     TABLESPACE_NAME
------------------------------ ------------------------------
LOB$                           SYSTEM
NTAB$                          SYSTEM
OBJ$                           SYSTEM
OBJAUTH$                       SYSTEM
OPQTYPE$                       SYSTEM
PROCEDURE$                     SYSTEM
PROCEDUREINFO$                 SYSTEM
PROXY_DATA$                    SYSTEM
PROXY_ROLE_DATA$               SYSTEM
REFCON$                        SYSTEM
SEG$                           SYSTEM
TABLE_NAME                     TABLESPACE_NAME
------------------------------ ------------------------------
SEQ$                           SYSTEM
SOURCE$                        SYSTEM
SUBCOLTYPE$                    SYSTEM
SUPEROBJ$                      SYSTEM
SYN$                           SYSTEM
TAB$                           SYSTEM
TS$                            SYSTEM
TSQ$                           SYSTEM
TYPED_VIEW$                    SYSTEM
TYPE_MISC$                     SYSTEM
UET$                           SYSTEM
TABLE_NAME                     TABLESPACE_NAME
------------------------------ ------------------------------
UGROUP$                        SYSTEM
UNDO$                          SYSTEM
USER$                          SYSTEM
VIEW$                          SYSTEM
VIEWTRCOL$                     SYSTEM
49 rows selected.
SQL>