Filename extension | .dbf |
---|---|
Internet media type | application/dbf, application/dbase |
Developed by | dBase |
Initial release | 1983 |
Latest release | 7 |
Website | dbase |
The .dbf file extension represents the dBase database file. The file type was introduced in 1983 with dBASE II. The file structure has evolved to include many features and capabilities. Several additional file types have been added, to support data storage and manipulation. The current .dbf file level is called Level 7. The .dbf format is supported by a number of database products.
The original dBASE database was known as Project Vulcan and was started by Wayne Ratliff in 1978. At the time the file that held the data was a simple table that could have data added, modified, deleted, or printed using the ASCII characters set. [1] As the product became more popular, the underlying file type .dbf was expanded, and additional files were added to increase the capabilities of the database system. Despite dBASE being an IDE (integrated development environment), a database system, a compiler, and a database application builder, the original .dbf file was still used for the actual data storage mechanism.
This section may require cleanup to meet Wikipedia's quality standards. The specific problem is: many version history entries with nothing to do with the file format.(February 2021) |
This was the last update to the 16-bit version of the Borland Database Engine (BDE). [4]
dBASE V – MS-Windows (Level 5)
xBase is a name applied to clones of the dBase, typically dBASE III+–V. Most xBase programs either use the format directly or uses a derived format with custom extensions. Erik Bachmann maintains an open-licensed description of these formats. [5]
The Level 7 structure is the latest supported by dBASE and BDE. It is incompatible with the previous file format, and is supported by few third-party applications. [6]
dBASE 7 – MS-Windows (Level 7)
Level 7 brought many improvements. The maximum length for field names increased from 10 to 31 characters. Some new fields types were added, such as the auto-increment field, [7] which prevents creation of duplicate record numbers in the same table.
BDE version 5.1.0
Significant improvements over the prior releases. [8] There are also some limitations with regards to what the BDE can handle. [9]
The "modern dBASE" III+–V is the most common dBASE file format found in the wild. In "modern dBASE", a .dbf file consists of a header, the data records, and the end-of-file marker.
Byte | Contents | Meaning |
---|---|---|
0 | 1 byte | Valid dBASE for DOS file; bits 0–2 indicate version number, bit 3 indicates the presence of a dBASE for DOS memo file, bits 4–6 indicate the presence of a SQL table, bit 7 indicates the presence of any memo file (either dBASE m PLUS or dBASE for DOS) |
1–3 | 3 bytes | Date of last update; formatted as YYMMDD (with YY being the number of years since 1900) |
4–7 | 4 bytes (LE) | Number of records in the database file |
8–9 | 2 bytes (LE) | Number of bytes in the header |
10–11 | 2 bytes (LE) | Number of bytes in the record |
12–13 | 2 bytes | Reserved; fill with 0 |
14 | 1 byte | Flag indicating incomplete transaction [note 1] |
15 | 1 byte | Encryption flag [note 2] |
16–27 | 12 bytes | Reserved for dBASE for DOS in a multi-user environment |
28 | 1 byte | Production .mdx file flag; 1 if there is a production .mdx file, 0 if not |
29 | 1 byte | Language driver ID |
30–31 | 2 bytes | Reserved; fill with 0 |
32–n [note 3] [note 4] | 32 bytes each | array of field descriptors (see below for layout of descriptors) |
n + 1 | 1 byte | 0x0D as the field descriptor array terminator |
Byte | Contents | Meaning |
---|---|---|
0–10 | 11 bytes | Field name in ASCII (zero-filled) |
11 | 1 byte | Field type. Allowed values: C , D , F , L , M , or N (see next table for meanings) |
12–15 | 4 bytes | Reserved |
16 | 1 byte | Field length in binary (maximum 254 (0xFE)). |
17 | 1 byte | Field decimal count in binary |
18–19 | 2 bytes | Work area ID |
20 | 1 byte | Example |
21–30 | 10 bytes | Reserved |
31 | 1 byte | Production MDX field flag; 1 if field has an index tag in the production MDX file, 0 if not |
Each record begins with a 1-byte "deletion" flag. The byte's value is a space (0x20), if the record is active, or an asterisk (0x2A), if the record is deleted. Fields are packed into records without field separators or record terminators.
All field data is ASCII. Depending on the field's type, the application imposes further restrictions:
Field type | Mnemonic | What it accepts |
---|---|---|
C | Character | Any ASCII text (padded with spaces up to the field's length) |
D | Date | Numbers and a character to separate month, day, and year (stored internally as 8 digits in YYYYMMDD format) |
F | Floating point | - , . , 0 –9 (right justified, padded with whitespaces) |
L | Logical | Y , y , N , n , T , t , F , f , or ? (when uninitialized) |
M | Memo | Any ASCII text (stored internally as 10 digits representing a .dbt block number, right justified, padded with whitespaces) |
N | Numeric | - , . , 0 –9 (right justified, padded with whitespaces) |
A memo (.DBT) file consists of blocks numbered sequentially (0,1,2, and so on). SET BLOCKSIZE determines the size of each block. The first block, block 0, is the memo file header.
Each memo field of each record in the .DBF file contains the number of the block (in ASCII) where the memo field begins. If the memo field contains no data, the .DBF file contains blanks (0x20) rather than a number.
When a memo field's content changes, its block number may also change. I.e. the memo gets relocated. In that case, the number in the .DBF file gets updated.
In dBASE III PLUS, the space consumed by deleted text in a memo field cannot be reused — the .DBT file size grows each time text is added, even if other text has been deleted. dBASE for DOS may reuse that space for new text. dBASE IQ PLUS always appended new text to the end of the .dbt file.
dBASE defines many types of files. It also recognizes some operating system files and files from other products. The table below lists the most commonly used formats first. It was compiled from the documentation of dBASE III+, dBASE IV, and dBASE CLASSIC. [10]
Extension | File content |
---|---|
.DBF | Database file |
.DBK | Database backup file |
.DBO | Command and procedure object file |
.DBT | Database memo file |
.DEF | Selector definition file |
.DEM | Define statements for a CUA form |
.DIF | Data Interchange Format, or VisiCalc file; used with APPEND FROM and COPY TO |
.DOC | Documentation file; Applications Generator only |
.ERR | Created if an error occurs during form generation, or if an unrecoverable error occurs |
.FIL | Files list design object file |
.EMO | Compiled format (.fmt) file |
.FMT | Generated format file; from .scr file |
.FNL | Report binary name list file |
.FR3 | Renamed old dBASE HI report form (.frm) file |
.ERG | Generated report form file; from .frm file |
.FRM | Report form file |
.FRO | Compiled report form (.ERG) file |
.FW2, .FW3, .FW4 | Framework spreadsheet or database file; used for import and export |
.GEN | Template file |
.GRP | Windows group file for dBASE for DOS |
.HLP | dBASE for DOS help files |
.ICO | dBASE for DOS icon file under Windows |
.INI | Windows-like INI file to save Label Designer and IDE state information. |
.KEY | Keystroke macro library file |
.LB3 | Renamed old dBASE III label form (.LBL) file |
.LBG | Generated label form file; from .LBL file |
.LBL | Label form file |
.LBO | Compiled label form (.LBL) file |
.LOG | Transaction log file |
.LNL | Label binary name list file |
.MBK | Multiple index backup file |
.MDX | Multiple index file |
.MEM | Memory file |
.NDX | Single index file |
.OVL | dBASE for DOS overlay file |
PIF | Microsoft Windows file for non-Windows applications |
.POP | Pop-up menu design object file; Applications Generator only |
.PR2 | Printer driver file |
.PRD | A file containing printer driver information for DBSETUP |
.PRF | Print form file |
.PRG | dBASE command or procedure file |
.PRS | dBASE SQL command or procedure file |
.PRT | Printer output file |
.QBE | QBE query file |
.QBO | Compiled QBE query (.QBE) file |
.QRY | dBASE El query file |
.RES | Resource file |
.RPD | RapidFile file; used for import and export |
.SC3 | Renamed old dBASE III screen (.SCR) file |
.SCR | Screen file |
.SNL | Screen binary name list file |
.STR | Structure list design object file; Applications Generator only |
.T44/.W44 | Intermediate work files; used by SORT and INDEX |
.TBK | Database memo backup file |
.TXT | ASCII text output file |
.UPD | QBE update query file |
.UPO | Compiled QBE update query (.UPD) file |
.VAL | Values list design object file; Applications Generator only |
.VMC | Configuration file; for Virtual Memory Manager (VMM) |
.VUE | View file |
.WIN | Logical window save file |
.WKS, .WK1 | Lotus 1-2-3 file; used with APPEND FROM and COPY TO |
File Allocation Table (FAT) is a file system developed for personal computers and was the default filesystem for MS-DOS and Windows 9x operating systems. Originally developed in 1977 for use on floppy disks, it was adapted for use on hard disks and other devices. The increase in disk drives capacity required four major variants: FAT12, FAT16, FAT32, and ExFAT. FAT was replaced with NTFS as the default file system on Microsoft operating systems starting with Windows XP. Nevertheless, FAT continues to be used on flash and other solid-state memory cards and modules, many portable and embedded devices because of its compatibility and ease of implementation.
A text file is a kind of computer file that is structured as a sequence of lines of electronic text. A text file exists stored as data within a computer file system.
dBase was one of the first database management systems for microcomputers and the most successful in its day. The dBase system included the core database engine, a query system, a forms engine, and a programming language that tied all of these components together.
Clipper is an xBase compiler that implements a variant of the xBase computer programming language. It is used to create or extend software programs that originally operated primarily under MS-DOS. Although it is a powerful general-purpose programming language, it was primarily used to create database/business programs.
Comma-separated values (CSV) is a text file format that uses commas to separate values, and newlines to separate records. A CSV file stores tabular data in plain text, where each line of the file typically represents one data record. Each record consists of the same number of fields, and these are separated by commas in the CSV file. If the field delimiter itself may appear within a field, fields can be surrounded with quotation marks.
For Microsoft Windows, OS/2, and DOS, .exe is the filename extension that denotes a file as being executable – a computer program – containing an entry point.
A fat binary is a computer executable program or library which has been expanded with code native to multiple instruction sets which can consequently be run on multiple processor types. This results in a file larger than a normal one-architecture binary file, thus the name.
A binary file is a computer file that is not a text file. The term "binary file" is often used as a term meaning "non-text file". Many binary file formats contain parts that can be interpreted as text; for example, some computer document files containing formatted text, such as older Microsoft Word document files, contain the text of the document but also contain formatting information in binary form.
A FourCC is a sequence of four bytes used to uniquely identify data formats. It originated from the OSType or ResType metadata system used in classic Mac OS and was adopted for the Amiga/Electronic Arts Interchange File Format and derivatives. The idea was later reused to identify compressed data types in QuickTime and DirectShow.
A hex editor is a computer program that allows for manipulation of the fundamental binary data that constitutes a computer file. The name 'hex' comes from 'hexadecimal', a standard numerical format for representing binary data. A typical computer file occupies multiple areas on the storage medium, whose contents are combined to form the file. Hex editors that are designed to parse and edit sector data from the physical segments of floppy or hard disks are sometimes called sector editors or disk editors.
Netpbm is an open-source package of graphics programs and a programming library. It is used mainly in the Unix world, where one can find it included in all major open-source operating system distributions, but also works on Microsoft Windows, macOS, and other operating systems.
The Access Database Engine is a database engine on which several Microsoft products have been built. The first version of Jet was developed in 1992, consisting of three modules which could be used to manipulate a database.
VP-Info is a database language and compiler for the personal computer. VP-Info was a competitor to the Clipper and dBase applications in the late 1980s and 1990s. VP-Info was originally intended to run on MS-DOS, DR-DOS and the PC-MOS/386 operating system, but now is run on the vDOS, or DOSbox-X, emulators. The last release of VP-Info, a multi-tasking, multi-user version released in 1992 with a built-in compiler, and was named SharkBase, or simply "Shark".
The shapefile format is a geospatial vector data format for geographic information system (GIS) software. It is developed and regulated by Esri as a mostly open specification for data interoperability among Esri and other GIS software products. The shapefile format can spatially describe vector features: points, lines, and polygons, representing, for example, water wells, rivers, and lakes. Each item usually has attributes that describe it, such as name or temperature.
Intel hexadecimal object file format, Intel hex format or Intellec Hex is a file format that conveys binary information in ASCII text form, making it possible to store on non-binary media such as paper tape, punch cards, etc., to display on text terminals or be printed on line-oriented printers. The format is commonly used for programming microcontrollers, EPROMs, and other types of programmable logic devices and hardware emulators. In a typical application, a compiler or assembler converts a program's source code to machine code and outputs it into a object or executable file in hexadecimal format. In some applications, the Intel hex format is also used as a container format holding packets of stream data. Common file extensions used for the resulting files are .HEX or .H86. The HEX file is then read by a programmer to write the machine code into a PROM or is transferred to the target system for loading and execution. There are various tools to convert files between hexadecimal and binary format, and vice versa.
The DOS MZ executable format is the executable file format used for .EXE files in DOS.
Motorola S-record is a file format, created by Motorola in the mid-1970s, that conveys binary information as hex values in ASCII text form. This file format may also be known as SRECORD, SREC, S19, S28, S37. It is commonly used for programming flash memory in microcontrollers, EPROMs, EEPROMs, and other types of programmable logic devices. In a typical application, a compiler or assembler converts a program's source code to machine code and outputs it into a HEX file. The HEX file is then imported by a programmer to "burn" the machine code into non-volatile memory, or is transferred to the target system for loading and execution.
The FAT file system is a file system used on MS-DOS and Windows 9x family of operating systems. It continues to be used on mobile devices and embedded systems, and thus is a well-suited file system for data exchange between computers and devices of almost any type and age from 1981 through to the present.
The GOFF specification was developed for IBM's MVS operating system to supersede the IBM OS/360 Object File Format to compensate for weaknesses in the older format.
The Esri TIN format is a popular yet proprietary geospatial vector data format for geographic information system (GIS) software for storing elevation data as a triangulated irregular network. It is developed and regulated by Esri, US. The Esri TIN format can spatially describe elevation information including breaking edge features. Each points and triangle can carry a tag information. A TIN stored in this file format can have any shape, cover multiple regions and contain holes.