REVERSE function with the REVERSE keyword

REVER
-----
54321

SQL> select reverse ('oracle ') from dual;
REVERS
------
ElcarO

SQL> select reverse ('test') from dual;
REVE
----
????

NAME TYPE VALUE
-----------------------------------------------------------------------------
Nls_language string AMERICAN

'Test'
------
Test

REVERSE ('test ')
---------------
Allow

DUMP ('20140901') DUMP (REVERSE ('20160901 '))
--------------------------------------------------------
Typ = 96 Len = 5: 49,50, 51,52, 53 Typ = 96 Len = 5: 53,52, 51,50, 49
Print the ASCII code of '123' in reverse order.

DUMP ('oracle ') DUMP (REVERSE ('oracle '))
--------------------------------------------------------------------
Typ = 96 Len = 6: 79,114, 108,101, 101,108 Typ = 96 Len = 6 :,

DUMP ('test') DUMP (REVERSE ('test '))
----------------------------------------------------------
Typ = 96 Len = 4: 178,226,202,212 Typ = 96 Len = 4: 212,202,226,178.