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The data file with suffix DBF is the central table in an Xbase database. All other data files are related to this one file.
The Data File is a mix of binary and ASCII data. Header contains binary data. The records are all in ASCII (except ofcause the binary objects like pictures).

BERJAYA Several sources claim that dBASE clears the header on creation with blanks (20h). But I've seen data in the reserved areas.
Some documents states that deleted records are overwritten by new valid records. My experience is that new records are appended to the data file - not inserted.
A deleted record can only be deleted physically using the PACK command. Even after PACK the deleted record exists after the EOF mark. The file is not truncated in dBASE III (But don't count on it ;-)

BERJAYA Note that this structure is valid for Xbase - and dBASE v. III - 5. Later versions of dBASE has a different layout, like dBASE 7 (see http://www.dbase.com/KnowledgeBase/int/db7_file_fmt.htm 



          _______________________  _______
00h /   0| Version number      *1|  ^
         |-----------------------|  |
01h /   1| Date of last update   |  |
02h /   2|      YYMMDD        *21|  |
03h /   3|                    *14|  |
         |-----------------------|  |
04h /   4| Number of records     | Record
05h /   5| in data file          | header
06h /   6| ( 32 bits )        *14|  |
07h /   7|                       |  |
         |-----------------------|  |
08h /   8| Length of header   *14|  |
09h /   9| structure ( 16 bits ) |  |
         |-----------------------|  |
0Ah /  10| Length of each record |  |
0Bh /  11| ( 16 bits )     *2 *14|  |
         |-----------------------|  |
0Ch /  12| ( Reserved )        *3|  |
0Dh /  13|                       |  |
         |-----------------------|  |
0Eh /  14| Incomplete transac.*12|  |
         |-----------------------|  |
0Fh /  15| Encryption flag    *13|  |
         |-----------------------|  |
10h /  16| Free record thread    |  |
11h /  17| (reserved for LAN     |  |
12h /  18|  only )               |  |
13h /  19|                       |  |
         |-----------------------|  |
14h /  20| ( Reserved for        |  |            _        |=======================| ______
         |   multi-user dBASE )  |  |           / 00h /  0| Field name in ASCII   |  ^
         : ( dBASE III+ - )      :  |          /          : (terminated by 00h)   :  |
         :                       :  |         |           |                       |  |
1Bh /  27|                       |  |         |   0Ah / 10|                       |  |
         |-----------------------|  |         |           |-----------------------| For
1Ch /  28| MDX flag (dBASE IV)*14|  |         |   0Bh / 11| Field type (ASCII) *20| each
         |-----------------------|  |         |           |-----------------------| field
1Dh /  29| Language driver     *5|  |        /    0Ch / 12| Field data address    |  |
         |-----------------------|  |       /             |                     *6|  |
1Eh /  30| ( Reserved )          |  |      /              | (in memory !!!)       |  |
1Fh /  31|                     *3|  |     /       0Fh / 15| (dBASE III+)          |  |
         |=======================|__|____/                |-----------------------|  | <-
20h /  32|                       |  |  ^          10h / 16| Field length       *22|  |   |
         |- - - - - - - - - - - -|  |  |                  |-----------------------|  |   | *7
         |                    *19|  |  |          11h / 17| Decimal count      *23|  |   |
         |- - - - - - - - - - - -|  |  Field              |-----------------------|  | <-
         |                       |  | Descriptor  12h / 18| ( Reserved for        |  |
         :. . . . . . . . . . . .:  |  |array     13h / 19|   multi-user dBASE)*18|  |
         :                       :  |  |                  |-----------------------|  |
      n  |                       |__|__v_         14h / 20| Work area ID       *16|  |
         |-----------------------|  |    \                |-----------------------|  |
      n+1| Terminator (0Dh)      |  |     \       15h / 21| ( Reserved for        |  |
         |=======================|  |      \      16h / 22|   multi-user dBASE )  |  |
      m  | Database Container    |  |       \             |-----------------------|  |
         :                    *15:  |        \    17h / 23| Flag for SET FIELDS   |  |
         :                       :  |         |           |-----------------------|  |
    / m+263                      |  |         |   18h / 24| ( Reserved )          |  |
         |=======================|__v_ ___    |           :                       :  |
         :                       :    ^       |           :                       :  |
         :                       :    |       |           :                       :  |
         :                       :    |       |   1Eh / 30|                       |  |
         | Record structure      |    |       |           |-----------------------|  |
         |                       |    |        \  1Fh / 31| Index field flag    *8|  |
         |                       |    |         \_        |=======================| _v_____
         |                       | Records
         |-----------------------|    |
         |                       |    |          _        |=======================| _______
         |                       |    |         / 00h /  0| Record deleted flag *9|  ^
         |                       |    |        /          |-----------------------|  |
         |                       |    |       /           | Data               *10|  One
         |                       |    |      /            : (ASCII)            *17: record
         |                       |____|_____/             |                       |  |
         :                       :    |                   |                       | _v_____
         :                       :____|_____              |=======================|
         :                       :    |
         |                       |    |
         |                       |    |
         |                       |    |
         |                       |    |
         |                       |    |
         |=======================|    |
         |__End_of_File__________| ___v____  End of file ( 1Ah )  *11
  1. Also called signature.
    Value Bit mask Description
    02h 00000010 FoxBase
    03h 00000011 File without DBT
    04h 00000100 dBASE IV w/o memo file
    05h 00000101 dBASE V w/o memo file
    07h 00000111 VISUAL OBJECTS (first 1.0 versions) for the Dbase III files w/o memo file
    30h 00110000 Visual FoxPro
    30h 00110000 Visual FoxPro w. DBC
    31h 00110001 Visual FoxPro w. AutoIncrement field
    43h 01000011 .dbv memo var size (Flagship)
    7Bh 01111011 dBASE IV with memo
    83h 10000011 File with DBT
    83h 10000011 dBASE III+ with memo file
    87h 10000111 VISUAL OBJECTS (first 1.0 versions) for the Dbase III files (NTX clipper driver) with memo file
    8Bh 10001011 dBASE IV w. memo
    8Eh 10001110 dBASE IV w. SQL table
    B3h 10110011 .dbv and .dbt memo (Flagship)
    E5h 11100101 Clipper SIX driver w. SMT memo file.

    Note! Clipper SIX driver sets lowest 3 bytes to 110 in descriptor of crypted databases. So, 3->6, 83h->86h, F5->F6, E5->E6 etc.
    F5h 11110101 FoxPro w. memo file
    FBh 11111011 FoxPro ???
    		dBASE IV bit flags:
    Bit Description
    0-2 Version no. i.e. 0-7
    3 Presence of memo file
    4-6 Presence of SQL table
    7 DBT flag 
    MSSSFVVV
    M dBASE III memo file
    S SQL mask
    F Memo field flag
    V Version
  2. Sum of lengths of all fields + 1 (deletion flag)
  3. Filled with 00h. (dBASE IV)
  4. Production index / Multiple index file
    (dBASE IV)
    Value Description
    01h MDX file present
    00h no MDX file (index upon demand).
    		(FoxBase)
    Value Description
    01h CDX compound index file present,
    00h no CDX file.
    		(Visual FoxPro)
    Value Description
    02h With memo
    04h Database Container (DBC)
    07h DBC (incl. memo & indexes)
  5. (Foxpro) Code page: These values follow the DOS / Windows Code Page values.
    Value Description Code page
    01h DOS USAcode page 437
    02h DOS Multilingualcode page 850
    03h Windows ANSIcode page 1252
    04h Standard Macintosh
    64h EE MS-DOScode page 852
    65h Nordic MS-DOScode page 865
    66h Russian MS-DOScode page 866
    67h Icelandic MS-DOS
    68h Kamenicky (Czech) MS-DOS
    69h Mazovia (Polish) MS-DOS
    6Ah Greek MS-DOS (437G)
    6Bh Turkish MS-DOS
    96h Russian Macintosh
    97h Eastern European Macintosh
    98h Greek Macintosh
    C8h Windows EEcode page 1250
    C9h Russian Windows
    CAh Turkish Windows
    CBh Greek Windows
  6. Field data address BERJAYA Note that this field has two very different interpretations.
    Version Offset Description
    dBASE 12-15 Address in memory.
    FoxPro 12-13 Offset of field from beginning of record.

    The field addresss is irellevant for other applications.
  7. Field length for non-numerical fields. (FoxPro, Clipper)
    Byte 16 is normally field length (0-255) and byte 17 represents the high byte for field length (256-65535).
  8. Index field flag (dBASE IV):
    Value Description
    00h No key for this field (ignored)
    01h Key exists for this field (in MDX)
  9. Deleted flag:
    Value Description
    2Ah (*) Record is deleted
    20h (blank) Record is valid
  10. There are no field separators for record terminators.
  11. End-of-file
    dBASE II regards any End-of-File 1Ah value as the end of the file. dBASE III regard an End-of-File as an ordinary character, however it appends an extra End-of-File character at the physical end of the file.
    If the file is packed the physical size of the file may be larger than the logical i.e. there may be garbage after the EOF mark.
  12. (dBASE IV) Incomplete transaction:
    Value Description
    00h Transaction ended (or rolled back)
    01h Transaction started
  13. Encryption flag (dBASE IV): BERJAYABe very careful NOT to modify this flag!
    This is the only indication that the content is enctrypted.
    Value Description
    00h Not encrypted
    01h Data encrypted
  14. Stored at binary (Little endian). Unsigned.
  15. Database Container (DBC) 263 bytes for backlist. (Visual FoxPro)
    Included in header structure.
  16. Work area ID is 01h in all dBASE III files
  17. An empty memo field has a reference filled with 10 blanks.
  18. Field Flags (FoxPro/FoxBase):
    Value Description
    01h System column (not visible to user)
    02h Column can store null values
    04h Binary column (for CHAR and MEMO only)
  19. Max 128 fields
  20. ?? See Data types
  21. Date in header is without century YYMMDD and date in records are with century YYYYMMDD. Valid interval is 00h - FFh. Add base year 1900 and you'll have the interval 1900 - 2155.
  22. Field length Max = 255. Valid types (See Data types
  23. Decimal count Numeric <= 15