Dump (Expr, Return_Fmt, Start, Length)

Column Street_Address Format A25
Column Dump           Format A30
Column Substr         Format A10

Select Street_Address
       -----------------------------------------------
     , Substr(Street_Address,3,4) As Substr
       -----------------------------------------------
     , Dump(Street_Address   /* Field or Expression */
                        , 3  /* ASCII Format        */
                        , 3  /* Start in Position 3 */
                        , 4  /* Return 4 characters */
            ) As Dump
       -----------------------------------------------
  From HR.Locations
 Where RowNum < 2;

Dump returns:	Return Formats:	Common Types:
Typ=12 (Data Type) Len=7: (Full Length of Column) 120,108 (Internal Representation)	3 ASCII (default) 8 Octal 10 Decimal 16 Hexadecimal 17 Single character	Typ=1 VARCHAR2 Typ=96 CHAR Typ=2 NUMBER Typ=12 DATE

STREET_ADDRESS            SUBSTR     DUMP
------------------------- ---------- ------------------------------
1297 Via Cola di Rie      97 V       Typ=1 Len=20: 57,55,32,86

See Character Sets for a complete list of codes generated from DUMP.