#### #### ###### ## ## ## ## ## ## ## ## ###### ###### ##### ### ###### ## ## ## ## ## ## ## ## ####### ######## ####### ## ## ## ## ## ## ## ## #### #### ###### ######## ####### ##### Xbase File Format Description by Erik Bachmann Clickety Click Software 2000-12-14 WHAT IS XBASE "Generic term for the dBASE family of database languages. Coined in response to threatened litigation over use of the copyrighted trademark 'dBASE'." http://wombat.doc.ic.ac.uk/ Xbase is a complex of data files (.DBF), indexes (NDX, MDX, CDX etc.) and eventually note files (DBT) for storing large amounts of formatted data in a structured form. The Xbase family of databases is covering the dBase, Clipper, FoxPro, and their Windows equivalents Visual dBase, Visual Objects, and Visual FoxPro, plus some older products. All are based on the .DBF file format. Basically Xbase is three different types of files: NN.dbf Data files NN.dbt Memo files (i.e. a separate file containing full text fields) *.ndx Index files pointing to a field in the *.dbf Xbase is almost compatible with dBASE and is actually a clone of dBASE. The creator of dBASE Ashton-Tate (and later Borland) has the copyright for the name dBASE, but NOT the structure. Therefore the name Xbase (It smells like - but it's not :-) has been widely used for look-alike data structures. There has been an attempt to create a standard for Xbase. I've found a lot of dead links while searching on Alta Vista's World Wide Web search engine. I'm at the moment not aware of the result of the Xbase comitys work. Xbase has - like most dBASE clones - it's offspring in the dBASE III+ file structure. I've tried to add all later enhancements as notes to the structure. _________________________________________________________________ Index * What Is Xbase * Why This Document * A few words of concern * What sort of data can be handled * What do the files look like Data files: The structure of data files (*.dbf) What to check when opening a .DBF File Index files: The Structure of Index files (*.ndx) * Search algorithm for index files The Structure of Multiple Index files (*.mdx) The Structure of Compound Index files (*.cdx) The Structure of Uncompressed Index files (*.idx) The Structure of Clipper Index Files (*.ntx) Memo/freeform files: The Structure of Memo Field Files (*.dbt) The Structure of FoxPro Object and Memo Field Files (*.fpt) The Structure of Memmory Files (*.mem) Features: The Record Lock Field on a dBASE IV Table Read/write locks using share Year 2000 problems dBASE II: dBASE II FILES The structure of dBASE II data files (*.dbf) The Structure of dBASE II index file Examples: Description of test.dbf Description of test.ndx Description of test.dbt Hex dump of test.dbf Hex dump of test.ndx Hex dump of test.dbt dBASE Specifications Appendixes List of File extensions HISTORY REFERENCE LIST _________________________________________________________________ WHY THIS DOCUMENT I've been looking for a simple database tool for my work with C programming and bibliographical database systems. During my investigation of a lot of BBS's, FTP sites, toolboxes etc. I've discovered at lot of almost-ready-to-fly Xbase clones. This made me wonder why noone has collected a description of Xbase files AND made a simple package of C functions to handle this type of data files. THAT was my goal - and THIS is the result. _________________________________________________________________ .----. ((*)(*)) \ /\ / #### \__/ WARNING ! ! ! DO *NOT* attempt to manipulate any critical database files *WITHOUT* making a proper and validated backup first. DO *NOT* access any database files in a multi-user environment! DO *NOT* access the files in text mode. Use binary mode only ! _________________________________________________________________ Any comments, corrections, additions etc. are welcome. You can reach me at: e_bachmann@hotmail.com or by snail mail: Erik Bachmann Grydehĝjvej 62 DK-4000 Roskilde Denmark Europe Third stone from the Sun - and turn left :-) Note! Mispelling an tybingerors are included for freee :-) _________________________________________________________________ A few words of concern Binary Means data is stored in blocks of paired bytes each 8 bits in size. The bytes are swaped in pairs the Intel way with the low byte value first and the high byte value last: ABCDEF (ASCII) BADCFE (binary) Garbage/Reserved Some areas in the files are labeled garbage or reserved or not used. These areas might contain bits and pieces from old files. Check out these areas (and overwrite them with 00h). You might not want to destribute an old love letter or - as I nearly did - parts of your check account. _________________________________________________________________ WHAT SORT OF DATA CAN BE HANDLED Data files (*.dbf) contains a header with information on the data structure AND the record themselves. The data field is predefined as carrying data of a specific type ( Character, Numbers, Longs, Dates, Memo). Each data type has its limitations: C Character ASCII text < 254 characters long. Character fields can be up to 32 KB long (in Clipper and FoxPro) using decimal count as high byte in field length. It's possible to use up to 64KB long fields by reading length as unsigned. Only fields <= 100 characters can be indexed. N Number ASCII text 18 characters long. Number fields can be up to 20 characters long in FoxPro and Clipper. L Logical Boolean/byte (8 bit) Legal values: ? Not initialised (default) Y,y Yes N,n No F,f False T,t True Logical fields are always displayed using T/F/?. Some sources claims that space (ASCII 20h) is valid for not initialised. D Date Date in format YYYYMMDD. A date like 0000-00- 00 is *NOT* valid. M Memo Pointer to ASCII text field in memo file 10 digits representing a pointer to a DBT block (default is blanks). F Floating point (dBASE IV and later, FoxPro, Clipper) 20 digits N/A Character name variable 1-254 characters (64 KB in FoxBase and Clipper) B Binary (dBASE V) Like Memo fields, but not for text processing. (FoxPro/FoxBase) Double integer *NOT* a memo field G General (dBASE V: like Memo) OLE Objects in MS Windows versions P Picture (FoxPro) Like Memo fields, but not for text processing. Y Currency (FoxPro) T DateTime (FoxPro) I 4 byte little endian integer (FoxPro) Index files (*.ndx) are sorted references to fields in the data files. There might be more than one index for each data file. dBASE III Memo files are primitive 512 byte hunks of ASCII text data creating a way for text fields to exceed the 255 characters barrier of ordinary text fields. Other versions may store up till 64 KB of text in a fixed sized text field. Larger amounts of text (and binary data) is still stored in memo-like files. The size off the blocks can be user defined while creating the memo file (see byte 4-7 of the memo file structure). .----. ((*)(*)) \ /\ / #### \__/ Note that memo fields are not fully supported by a majority of Xbase utilities (incl. dBASE III). You can't export/import records with memo fields (They are ignored in delimited exports in dBASE III). To avoid problems with the priority of fields, put memo fields at the very end of the record. _________________________________________________________________ WHAT DO THE FILES LOOK LIKE They all look brown to me :-) All Xbase files have a header describing the structure of the data in the file. Schematically they look like this: The structure of data files (*.dbf) _______________________ _______ 0 | Version number *1| ^ |-----------------------| | 1 | Date of last update | | 2 | YYMMDD | | 3 | | | |-----------------------| | 4 | Number of records | Record 5 | in data file | header 6 | ( 32 bits ) *14 | | 7 | | | |-----------------------| | 8 | Length of header | | 9 | structure ( 16 bits ) | | |-----------------------| | 10| Length of each record | | 11| ( 16 bits ) *2| | |-----------------------| | 12| ( Reserved ) *3| | 13| | | |-----------------------| | 14| Incomplete transac.*12| | |-----------------------| | 15| Encryption flag *13| | |-----------------------| | 16| Free record thread | | 17| (reserved for LAN | | 18| only ) | | 19| | | |-----------------------| | 20| ( Reserved for | | _ |=======================| ______ | multi-user dBASE ) | | / 0| Field name in ASCII | ^ : ( dBASE III+ - ) : | / : (terminated by 00h) : | : : | | | | | 27| | | | 10| | | |-----------------------| | | |-----------------------| For 28| MDX flag (dBASE IV) *4| | | 11| Field type in ASCII | each |-----------------------| | | |-----------------------| field 29| Language driver *5| | / 12| Field data address | | |-----------------------| | / | *6| | 30| ( Reserved ) | | / | (in memory !!!) | | 31| *3| | / 15| (dBASE III+) | | |=======================|__|____/ |-----------------------| | <- 32| | | ^ 16| Field length (binary)| | | |- - - - - - - - - - - -| | | |-----------------------| | | *7 | | | | 17| Decimal count (binary)| | | |- - - - - - - - - - - -| | Field |-----------------------| | <- | | | Descriptor 18| ( Reserved for | | :. . . . . . . . . . . .: | |array 19| multi-user dBASE)*18| | : : | | |-----------------------| | n | |__|__v_ 20| Work area ID *16 | | |-----------------------| | \ |-----------------------| | n+1| Terminator (0Dh) | | \ 21| ( Reserved for | | |=======================| | \ 22| multi-user dBASE ) | | m | Database Container | | \ |-----------------------| | : *15 : | \ 23| Flag for SET FIELDS | | : : | | |-----------------------| | m+263 | | | 24| ( Reserved ) | | |=======================|__v_ ___ | : : | : : ^ | : : | : : | | 30| | | | Record structure | | | |-----------------------| | | | | \ 31| Index field flag *8| | | | | \_ |=======================| _v_____ | | Records |-----------------------| | | | | _ |=======================| _______ | | | / 0| Field deleted flag *9| ^ | | | / |-----------------------| | | | | / | Data *10| One | | | / : *17: record | |____|_____/ | | | : : | | | _v_____ : :____|_____ |=======================| : : | \ | Field deleted flag *9| | | | \ |-----------------------| | | | \ | | | | | \ | | | | | \_ |-----------------------| | | | |=======================| | |__End_of_File__________| ___v____ End of file ( 1Ah ) *11 *1 dBASE III+: Also called signature. 02h FoxBase. 03h File without DBT. 30h Visual FoxPro 83h File with DBT. i.e. bit 0-3 version, 3-5 SQL, 7 DBT flag dBASE IV: bit 0-2 Version no. 3 Presence of memo file 4-6 Presence of SQL table 7 DBT flag Examples: 03h dBASE III w/o memo file 04h dBASE IV or IV w/o memo file 05h dBASE V w/o memo file 83h dBASE III+ with memo file F5h FoxPro w. memo file 8Bh dBASE IV w. memo 8Eh dBASE IV w. SQL table 30h Visual FoxPro w. DBC 7Bh dBASE IV with memo *2 Sum of lengths of all fields + 1 (deletion flag) *3 (dBASE IV) Filled with 00h. *4 (dBASE IV) Production index / Multiple index file 01h MDX file present 00h no MDX file (index upon demand). (FoxBase) 01h CDX compound index file present, 00h no CDX file. (Visual FoxPro) 02h With memo 04h Database Container (DBC) 07h DBC (incl. memo & indexes) *5 (Foxpro) Code page: 01h DOS USA code page 437 02h DOS Multilingual code page 850 03h Windows ANSI code page 1251 C8h Windows EE code page 1250 64h EE MS-DOS code page 852 66h Russian MS-DOS code page 866 65h Nordic MS-DOS code page 865 *6 (FoxPro) 12-13. offset of field from beginning of record. The field addresss is irellevant for other applications. *7 (FoxPro, Clipper) 16-17: Field length for non-numerical fields. Byte 16 is normally field length (0-255) and byte 17 represents the high byte for field length (256-65535). *8 (dBASE IV) Index field flag: 00h No key for this field (ignored) 01h Key exists for this field (in MDX) *9 2Ah (*) Record is deleted 20h (blank) Record is valid *10 There are no field separators for record terminators. *11 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 00h Transaction ended (or rolled back) 01h Transaction started *13 (dBASE IV) Encryption flag 00h Not encrypted 01h Data encrypted *14 Stored at binary i.e. value is generated as: byte#1 + (byte#2 * 256) + (byte#3 * 256²) + (byte#4 * 256³) ....... *15 (Visual FoxPro) Database Container (DBC) 263 bytes for backlist. 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 (FoxPro/FoxBase) Field Flags: 01h System column (not visible to user) 02h Column can store null values 04h Binary colunn (for CHAR and MEMO only) _________________________________________________________________ What to check when opening a .DBF File Records: * Length of record must be > 1 and < max length. (max length = 4000 B in dBASE III and IV, can be 32KB in other systems). * The number of records must be >= 0. Fields: * The .DBF file must have at least one field. * The number of fields must be <= the maximum allowable number of fields. File size: * File size reported by the operating system must match the logical file size. Logical file size = ( Length of header + ( Number of records * Length of each record ) ) _________________________________________________________________ The Structure of Index files (.ndx) The index file is a B+ tree - at least according to most description - but it's more clearly decribed as a paged B-tree. The essential structure is in an inverted tree, with an anchor note, multiple root nodes, and leaf nodes. The header is called the anchor node. _________________________________________________________________ ____ / \ \ / \ / \/ |__| Normally the header is read once only by the application, when the file is opened. _________________________________________________________________ The size of a page is ( as far as I know ) always 512 bytes. _______________________ _______ 0 | Starting page no | ^ 1 | *1 | | 2 | | | 3 | | | |-----------------------| | 4 | Total no of pages | File 5 | | header 6 | | | 7 | | (page 0) |-----------------------| | 8 | (Reserved) | | 9 | | | 10 | | | 11 | | | |-----------------------| | 12 | Key length | | 13 | | | |-----------------------| | 14 | No of keys per page | | 15 | | | |-----------------------| | 16 | Key type: 0 = char | | 17 | 1 = Num | | |-----------------------| | 18 | Size of key record *2| | 19 | | | 20 | | | 21 | | | |-----------------------| | 22 | (Reserved) | | |-----------------------| | 23 | Unique flag | | |-----------------------| | 24 | String defining the | | | key | | : : | : : | : : | 511| | | |=======================| _v____ 0| No of valid entries | ^ __ |=======================| 1| on current page | | / 0| Pointer to lower level| 2| | | / 1| (next page) | 3| | | / 2| | |-----------------------| | / 3| | 4| | | / |-----------------------| | Array of key entries | _|_____/ 4| Record number in | | | | 5| data file | | | Page 6| | | | | 7| | | | | |-----------------------| | | _|_____ 8| Key data *3 | :.......................: | \ : : :.......................: | \ N| | 511| | | \_____ |=======================| |=======================| _v_____ 0| | | | No of valid entries | | | on current page | | 3| | Page |-----------------------| | | Array of key entries | | :.......................: | :.......................: | 511|: | | |=======================| _v_____ *1 Root page number's offset is: page number * 512 bytes *2 Size of key record is a multiplum of 4. Record size is 4 (Pointer to next page) + 4 (record number i dbf) + key size ( as a multiplum of 4 ). i.e. if the key size is 10, the record size is 20 (4+4+12) *3 Numbers are stored as IEEE doubles (binary values). _________________________________________________________________ Search algorithm for index files 1. The anchor node always resides in memory, while the file is open and determines which root node to access for at given key. 2. The root node is read and sequentially scanned until a key is found that is >= to the desired key. 3. A second-level node is accessed and scanned in a manner similar to the root node. 4. The process continues until the pointer to the next-lower-level node has a value of zero. If the key matches the leaf key at this level, the record number for the key is returned. That's a discipline NOT to be discussed here :-) Way out of the scope fore this document and way too complex. One of the advances of the B+ tree is that the higher levels of the tree does not have to be updated when a certain node is changed - unless the tree has become unbalanced. ____ / \ \ / \ / \/ |__| If the data or index files are corrupt you may get a "DISK FULL" error. The program can not read the EOF marker and therefore assumes that the disk is full. Check you file and make sure there is no garbage in it, also re-index your files. _________________________________________________________________ The Structure of Multiple Index files (*.mdx) _______________________ _______ 0 | Version number *1| ^ |-----------------------| | 1 | Date of creation | | 2 | YYMMDD | | 3 | | | |-----------------------| | 4 | Data file name | File 5 | (no extension) | Header : : | : : | 19 | | | |-----------------------| | 20 | Block size | | | | | |-----------------------| | 22 | Block size adder N | | | | | |-----------------------| | 24 | Production index flag | | |-----------------------| | 25 | No. of entries in tag | | *2 |-----------------------| | 26 | Length of tag | | *3 |-----------------------| | 27 | (Reserved) | | |-----------------------| | 28 | No.of tags in use | | | | | |-----------------------| | 30 | (Reserved) | | | | | |-----------------------| | 32 | No.of pages in tagfile| | | | | | | | 35 | | | |-----------------------| | 36 | Pointer to first free | | | page | | | | | 39 | | | |-----------------------| | 40 | No.of block available | | | | | | | | 43 | | | |-----------------------| | 44 | Date of last update | | | YYMMDD | | 46 | | | |-----------------------| | 47 | (Reserved) | | |-----------------------| | 48 | (Garbage) | | : : | : : | | | | ___|=======================| 543| | _V___ / 0 | Tag header page no. | |-----------------------| | / | | 544| Tag table entries | Tag / | | | | Table | 3 | | :.......................: | | |-----------------------| Tag : : | | 4 | Tag name | table :.......................: | | : : : : | / : : : : | / | | :.......................:__|_/ 14 | | : : | |-----------------------| : : | 15 | Key format *4 | : : | |-----------------------| :.......................:__|_ 16 | Forward tag thread (<)| : : | \ |-----------------------| : : | \ 17 | Forward tag thread (>)| : : | \ |-----------------------| : : | | 18 | Backward tag thread *5| | | | | |-----------------------| | | | | 19 | (Reserved) | M*N| |__V__ | |-----------------------| |=======================| ^ | 20 | Key type *6 | 0| Pointer to root page | | | |-----------------------| | | | | 21 | (Reserved) | | | | | : : 3| | | | : : |-----------------------| | | 31 | | 4| File size in pages | Tag | |-----------------------| | | header| 32 | (Garbage) | | | | | : : 7| | | | | | |-----------------------| | \ N | | 8| Key format *7 | | \____|=======================| |-----------------------| | 9| Key type *8 | | |-----------------------| | 10| (Reserved) | | | | | |-----------------------| | 12| Index key length *9 | | | | | |-----------------------| | 14| Max.no.of keys/page | | | | | |-----------------------| | 16| Secondary key type *10| | | | | |-----------------------| | 18| Index key item length | | | | | |-----------------------| | 20| (Reserved) | | | | | | | | |-----------------------| | 23| Unique flag | | |-----------------------| | | | | : : | : :__V__ N*M|=======================| 1 2 Number of entries in tag table. Max no. is 48 (30h) 3 Length of each tag table entry. Max is 32 (20h). 4 00h Calculated 10h Data field 5 Previous tag 6 C Character N Numerical D Date 7 00h Right, left, dtoc 08h Decending order 10h Fields , string 40h Unique keys 8 C Character N Numerical D Date 9 Numeric Length is 12 Date Length is 8 Character Length is <= 100 bytes and not NULL terminated 10 0 Character/numerical (db4), Character (db3) 1 Date (db4) Numerical/date (db3) _________________________________________________________________ The Structure of Compound Index files (*.cdx) by David Kuechler (71202.1315@CompuServe.COM) A CDX is a compact IDX. The initial IDX contains one key per tag. The key is 10 byte character string which is the tag name. The record number stored with the key is the offset to the root page for that tag. ____ / \ \ / \ / \/ |__| There is no description on the compression algorithm A compact IDX has the following structure: _______________________ _______ 0 | Pointer to root node | ^ 1 | | | 2 | | | 3 | | | |-----------------------| | 4 | Pointer to free list | File 5 | (-1 if empty) | header 6 | | | 7 | *8 | (page 0) |-----------------------| | 8 | Version no. *10 | | 9 | | | 10 | | | 11 | | | |-----------------------| | 12 | Key length | | 13 | *9 | | |-----------------------| | 14 | Index options *1 | | |-----------------------| | 15 | Index Signature | | |-----------------------| | 16 | (Reserved) | | 17 | | | : (Currently all NULL's): | : : | : : | 501| | | |-----------------------| | 502| Sort order *2 | | 503| | | |-----------------------| | 504| Total expression | | 505| length (FoxPro 2) | | |-----------------------| | 506| FOR expression length | | 507| (binary) | | |-----------------------| | 508| (Reserved) | | 509| | | |-----------------------| | 510| Key expression length | | 511| (binary) | | |=======================| _v____ 512| Key & FOR expression | ^ 513| *3 | | : : | : : | 1023| | | |=======================| _v____ 0 | Node attributes *4 | ^ 1 | | | |-----------------------| | 2 | Number of keys | | 3 | | | |-----------------------| Non 4 | Pointer to left | leaf 5 | brother node | page 6 | (-1 if no left node) | | 7 | | (compressed) |-----------------------| | 8 | Pointer to right | | 9 | brother node | | 10 | (-1 if no right node) | | 11 | | | |-----------------------| | 12 | | | | | | __ |=======================| | | | / | Key data | | | NON / : : | | leaf / : : | | page / | | | | | / |-----------------------| | Array of key entries | _|_____/ M| Record number in | | | | | data file | | | | | (high order byte | | | | N| first) | | | | |-----------------------| | | _|_____ m| Pointer to child page | :.......................: | \ | | :.......................: | \ | | :.......................: | \ n| | 511| | | \____ |=======================| |=======================| _v_____ 0 | Node attributes *4 | ^ 1 | | | |-----------------------| | 2 | Number of keys | | 3 | | | |-----------------------| | 4 | Pointer to left | Leaf 5 | brother node | page 6 | (-1 if no left node) | | 7 | | (compressed) |-----------------------| | 8 | Pointer to right | | 9 | brother node | | 10 | (-1 if no right node) | | 11 | | | |-----------------------| | 12 | Free space available | | 13 | in page | | |-----------------------| | 14 | Record number mask | | 15 | | | 16 | | | 17 | | | |-----------------------| | 18 | Duplicate count mask | | *11 |-----------------------| | 19 | Trailing byte count mask | *11 |-----------------------| | 20 |*5 record no | | |-----------------------| | 21 |*5 duplicate count | | |-----------------------| ^ __ |=======================| 22 |*5 trailing count | | / 0| Recno/supCount/ | |-----------------------| Leaf / 1| TrailCount | 23 |*6 holding record no | page / 2| *7) | |-----------------------| | / 3| | 24 | | | / |-----------------------| | Array of key entries | _|_____/ 4| Record number in | | | | 5| data file | | | | 6| | | | | 7| | | | | |-----------------------| | | _|_____ 8| Key data | :.......................: | \ : : :.......................: | \ N| | 511| | | \_____ |=======================| |=======================| _v_____ *1) Index options represented as the sum of the following values: 01 Unique index 08 FOR clause 16 (10h) Bit vector (SoftC) 32 (20h) Compact index format (FoxPro) 64 (40h) Compounding index header (FoxPro) 128 (80h) Structure index (FoxPro) *2) 0 Ascending 1 Descending *3) Key first with null terminator, then FOR expression. 4) Node attributes represented as the sum of the following values: 0 Interior node (branch) 1 Root page 2 Leaf page 5) Byte 020 Number of bits for record number Byte 021 Number of bits for duplicate count Byte 022 Number of bits for trailing count 6) Byte 023: Number of bytes holding record number, duplicate count & trailing count (i.e. the total size of values in byte 20 - 22). 7) At the start of this area, the recno/dupCount/trailCount is stored (bit compressed). Each entry requires the number of bytes as indicated by byte 023. The key values are placed at the end of this area (working backwards) and are stored by eliminating any duplicates with the previous key and any trailing blanks. 8) -1 if none (FoxPro) 0 if none (FoxBase) 9) Number and date keys are 8 bits long . Character keys are <= 100 bytes long. Note! Character keys are NOT terminated with 00h -1 if none (FoxPro) 0 if none (FoxBase) 10) (Foxbase, FoxPro 1.x) No. of pages in file. (FoxPro 2.x) Reserved. 11) The individual list must be ANDed with these masks in order to calculate the original index. Other Notes on CDX Dates are stored as Julian dates and converted to numbers Numbers are stored as IEEE doubles (binary values) with the following conversion: * Convert to an IEEE double (8 bytes) * Swap the order of the bytes * IF the number was negative: * Invert all the bits ELSE * Invert only the highest order bit The advantage of this storage format is it allows numbers to be compared directly using memcmp(). _________________________________________________________________ The Structure of Uncompressed Index files (*.idx) _______________________ _______ 0 | Pointer to root node | ^ 1 | | | 2 | | | 3 | | | |-----------------------| | 4 | Pointer to free list | File 5 | (-1 if empty) | header 6 | | | 7 | *3 | (page 0) |-----------------------| | 8 | Pointer to EOF | | 9 | | | 10 | | | 11 | | | |-----------------------| | 12 | Key length | | 13 | *4 | | |-----------------------| | 14 | Index options *1 | | |-----------------------| | 15 | Index Signature | | |-----------------------| | 16 | Key expression | | 17 | | | : : | : : | 235| | | |-----------------------| | 236| FOR expression | | | | | : : | : : | 455| | | |-----------------------| | 456| (Reserved) | | | | | : : | : : | 511| | | |=======================| _v____ 0 | Node attributes *2 | ^ 1 | | | |-----------------------| | 2 | Number of keys | | 3 | | | |-----------------------| Non 4 | Pointer to left | leaf 5 | brother node | page 6 | (-1 if no left node) | | 7 | | (compressed) |-----------------------| | 8 | Pointer to right | | 9 | brother node | | 10 | (-1 if no right node) | | 11 | | | |-----------------------| | 12 | | | | | | __ |=======================| | | | / M| Key data | | | NON / : : : : leaf / : : : : page / N| | : : | / |-----------------------| | Array of key entries | _|_____/ O| Record number in | | | _|______ | data file | | | | \ | (high order byte | | | | \ O+4| first) | 511| | | \____ |=======================| |=======================| _v_____ *1) Index options represented as the sum of the following values: 01 Unique index 08 FOR clause 16 (10h) Bit vector (SoftC) 32 (20h) Compact index format (FoxPro) 64 (40h) Compounding index header (FoxPro) 128 (80h) Structure index (FoxPro) 2) Node attributes represented as the sum of the following values: 0 Index node 1 Start page 2 End page 3) -1 if none (FoxPro) 0 if none (FoxBase) 4) Number and date keys are 8 bits long . Character keys are <= 100 bytes long. Note! Character keys are NOT terminated with 00h -1 if none (FoxPro) 0 if none (FoxBase) _________________________________________________________________ The Structure of Clipper Index files (*.ntx) The CA-Clipper index file is a modified B+ tree. The size of a page is 1024 bytes. The first page is the header: _______________________ _______ 0 | Signature byte | ^ 1 | (binary) | | *9 |-----------------------| | 2 | Indexing version no. | | 3 | (Compiler version) | | |-----------------------| | 4 | Offset in file for | File 5 | first index page. | header 6 | (root) | | 7 | | (page 0) |-----------------------| | 8 | Offset to an unused | | *11 9 | next key page. | | 10 | | | 11 | | | |-----------------------| | 12 | Key size + 8 bytes | | *1 13 | | | |-----------------------| | 14 | Key size | | 15 | | | |-----------------------| | 16 | No. of decimals in | | 17 | key | | |-----------------------| | 18 | Max. item | | *6 19 | | | |-----------------------| | 20 | Half page | | *7 21 | | | |-----------------------| | 22 | Key expression. | | *8 23 | (NULL terminated) | | : : | 277 | | | |-----------------------| | 278 | Unique index flag | | *3 |-----------------------| | 279 | (Unused) | | : : | : : | 1023| | | |=======================| _v_____ 0| Address of next empty | ^ 1| page *11 | | 2| | | 3| | | |-----------------------| Empty page : (Reserved) | (in linked list) : | | : | | 1023: | | |=======================| ___V___ | No. of used entries | | | on current page (N) | | |-----------------------| Used | Array of N unsigned | page : longs *5 : | : : | |-----------------------| | | Array of index | | : entries : | : : | __ |=======================| : : | / 0| Address of left page | *4 | | | / 1| in tree | | | | / 2| | | | | / 3| | |=======================| ___|____/ |-----------------------| | Array of index | | 4| Record no. in DBF | : : | 5| | : : | 6| | : : | 7| | : : | |-----------------------| : : | 8| Key field | : : ___|____ : : |=======================| | \ N| | | | | \_____ |=======================| : : | |__End_of_File__________| ___v____ End of file ( 1Ah ) *1 Distance between key pages. size + 2 longs. *2 The first, or root page of an indes has a minimum of 1 entry regardless of this value. *3 1 Unique 0 NOT unique *4 This number will be between the minimum (half page) and maximum (max. item) defined in the header unless it is the root page. *5 The array length is equal to the maximum number of key entries per page +1. Value 00h = No record. Other values: Record offset from start of page *6) The maximum number of keys (with their pointers) that can fit on an index page. *7 The maximum number of keys that can fit on an index page, divided by two. This is an important value in a B-tree system as it is the minimum number of keys that must be on a page. *8 The actual expression on which the index was built. It is a NULL terminated string with at max length of 256 bytes. *9 0003h Clipper 87 0006h Clipper 5.x *10 This is a reference to the first page in a linked list of empty pages in beteen valid data. *11 Address 00 00 00 00h is the last empty page in chain. _________________________________________________________________ The Structure of Memo Field Files (*.dbt) dBASE III+ _______________________ _______ 0 | Number of next | ^ ^ 1 | available block | | | 2 | for appending data | | Header 3 | (binary) | | | |-----------------------| _|__v__ 4 | ( Reserved ) | | | | | | | | 7 | | | |-----------------------| | 8 | ( Reserved ) | | : : | 15 | | | |-----------------------| | 16 | Version no. (03h) | | |-----------------------| | 17 | (i.e. garbage) | | : : First block : : | 511| | | |=======================| _v_____ 512| | ^ | | | | | 512 Bytes | | text blocks : : | : : | | | | |-----------------------| _|_____ | Field terminator (1Ah)| | ^ |-----------------------| | |Terminating field | Field terminator (1Ah)| | |within the block *1 |-----------------------| _|__v__ : ( Unused ) : | 1023 : | |=======================| _v_____ | | ^ | | | | | 512 Bytes | | text blocks : : | : : | | | | | | _v_____ |=======================| *1) (FoxPro, Fox??) Is reported to use only one field terminator (1Ah). A memo field can be longer than the 512 byte block. It simply continues through the next block. The field is logically terminated by two End-of-file marks in the field. The reminder of the block is unused. ____ / \ \ / \ / \/ |__| Every time you re-write a memo field to the memo file in dBASE the field is APPENDED to the memo file (i.e. the file expands for each update). dBASE V for DOS (and perhaps others) may reuse the space from the deleted text, if memo size <= allocated number of block in dbt file. The Memo file itself tells nothing about it's use. You need the corresponding DBF file to interpret the content of the memo file. Many of the clones and dBASE 5 have binary elements stored in the memo file marked with file type B or G. dBASE IV _______________________ 0 | Number of next | ^ 1 | available block | | 2 | for appending data | Header 3 | (binary) | | |-----------------------| | 4 | ( Reserved ) | | | Size of blocks *1 | | | | | 7 | | | |-----------------------| | 8 | DBF file name | | | | | : : | 15 | | | |-----------------------| | 16 | Reserved (00h) | | |-----------------------| | 17 | ( Reserved ) | | 18 | | | 19 | | | |-----------------------| | 20 | Block length | | 21 | | | |-----------------------| | 22 | ( Reserved ) | | | | | | (i.e. garbage) | | : : | : : | 511| | | |=======================| _v_____ 1| | ^ Used block | | ^ __ |=======================| | | | / 0| ( Reserved ) | : : | / 1| | : : | / 2| FFh FFh 08h 00h | | | | / 3| | 511| | | / |-----------------------| |=======================| _|_____/ 4| Length of memo field | 1| | | 5| | : : | 6| | : : | 7| | | | | |-----------------------| 511| | _|_____ 8| Memo data *2 | |=======================| | \ : : | | | \ N| | | | | \_____ |=======================| | | | | | 512 Bytes | | text blocks : : | : : | Unused block : : | __ |=======================| : : | / 0| Pointer to next free | : : | / 1| block | : : | / 2| | | | | / 3| | 511| | | / |-----------------------| |=======================| _|_____/ 4| Pointer to next used | 1| | | 5| block | : : | 6| | : : | 7| | | | | |-----------------------| 511| | _|_____ 8| ( Reserved ) | |=======================| | \ : : 1| | | \ N| | | | | \_____ |=======================| | | | : : | | | | |-----------------------| _|_____ | Field terminator (1Ah)| | ^ |-----------------------| | |Terminating field | Field terminator (1Ah)| | |within the block *3 |-----------------------| _|__v__ : ( Unused ) : | 511| : | |=======================| _v_____ | | ^ | | | | | 512 Bytes | | text blocks : : | : : | | | | | | _v_____ |=======================| *1) (FoxBase, dBASE IV ??) Size of blocks in memo file (SET BLOCKSIZE). Default is 512 bytes. *2) End of text mark is 0Dh 0Ah and line breaks are 8Dh 0Ah *3) (FoxPro, Fox??) Is reported to use only one field terminator (1Ah). A memo field can be longer than the 512 byte block. It simply continues through the next block. The field is logically terminated by two End-of-file marks in the field. The reminder of the block is unused. _________________________________________________________________ _________________________________________________________________ .----. ((*)(*)) \ /\ / #### \__/ WARNING ! ! ! DO *NOT* attempt to treat these binary data as simple text ! ! ! _________________________________________________________________ The Structure of FoxPro Object and memo file (*.fpt) The file format is used by Fox Pro 2.x and later The size of the header is 512 bytes _______________________ _______ 0 | Number of next | ^ 1 | available block | | 2 | for appending data | Header 3 | (binary) *1 | | |-----------------------| | 4 | ( Reserved ) | | 5 | | | |-----------------------| | 6 | Size of blocks N *1 | | 7 | *2 | | |-----------------------| | 8 | ( Reserved ) | | | | | | | | | (i.e. garbage) | | : : | : : | 511| | | |=======================| _v_____ 1| | ^ Used block | | | __ |=======================| | | | / 0| Record type *3 | : : | / 1| | : : | / 2| | | | | / 3| | N| | | / |-----------------------| |=======================| _|_____/ 4| Length of memo field | 1| | | 5| | : : | 6| | : : | 7| | | | | |-----------------------| N| | _|_____ 8| Memo data | |=======================| | \ : : | | | \ N| | | | | \_____ |=======================| | | | : : | N| | _v_____ |=======================| *1) Binary value with high byte first. *2) Size of blocks in memo file (SET BLOCKSIZE). Default is 512 bytes. *3) Record type 00h Picture 01h Memo 02h Object A memo field can be longer than the 512 byte block. It simply continues through the next block. The field is logically terminated by two End-of-file marks in the field. The reminder of the block is unused. _________________________________________________________________ _________________________________________________________________ The Structure of Memmory Files (*.mem) _______________________ _______ 0 | | ^ 1 | Variable name | | : terminated by 00h : Header 9 | | | 10 | | | |-----------------------| | 11 | Variable type | | |-----------------------| | 12 | ( Reserved ) | | : : | 15 | | | |-----------------------| | <- 16 | Field length (binary)| | | |-----------------------| | | *1 17 | Decimal count (binary)| | | |-----------------------| | <- 18 | ( Reserved ) | | : : | : : | 31 | | _v_____ |-----------------------| | 32 | Variable | | : : | : :__V_____ N |=======================| *1 (FoxPro, Clipper) 16-17: Field length for non-numerical fields. Byte 16 is normally field length (0-255) and byte 17 represents the high byte for field length (256-65535). _________________________________________________________________ The Record Lock Field on a dBASE IV Table In a DOS multiuser environment, each user can place record locks on a shared table. For example, if user JSMITH is editing record number 12 of Stock, user MBROWN cannot access that record until it is unlocked. This prohibits one user from unintentionally overwriting another user's work. The dBASE table type gives you the Record Lock option to show you information about a locked record. If you check Record Lock, Database Desktop adds a hidden character field named _DBASELOCK to the table. This field shows you when a record was locked and by whom. ____ / \ \ / \ / \/ |__| Although Database Desktop adds the Record Lock field to the table, you will not see it when you view the table. You see a record's Record Lock field only if you are locked out of that record. Use the Create dBASE Table dialogue box to create the Record Lock field for a dBASE table. Record Lock is not available for dBASE III+ tables. The information you see when you find a locked field depends on the Info Size you specify. The Record Lock field can be from 8 to 24 characters. The default is 16. 0-1 The first two bytes (binary integer) tell whether a user has changed the record. Every committed change is counted encreasing the count by one. 2-4 The next three characters tell the time a user placed the lock. (10h 09h 07h i.e. 16:09:07) 5-7 The next three characters tell the date a user placed the lock. ( 60h 09h 0Bh i.e. (19)96-09-11 ) 8-24 The remaining 16 characters are optional. They tell the name of the user that placed the lock. The default size of 16 displays the changed status of the record, the time and date of the lock, and the first 8 characters of the user who placed the lock. ____ / \ \ / \ / \/ |__| You cannot see from the locking info if the user releases the record again. You have to test the record locking. On DOS systems SHARE has to be loaded. Turbo C, DJGPP and compatible C compilers have functions like: lock() _dos_lock() locking() for setting locks on a region of a file and unlock() _dos_unlock() unlocking for removing the lock again. It's important that YOU remove the locks BEFORE closing the file. _________________________________________________________________ Read/write locks using share by Phil Barnett (midnight@the-oasis.net) Share holds the locks, but it doesn't know anything about the structure or program that is requesting the lock. All share does is record the lock offset, type (record or file) and file name with path and where (station) it came from, and remove it when the correct station requests removal. Lets make a scenario. You have a 1000 byte header on your dbf file, and each record is 99 bytes + one for the delete flag. (this is to make the math simple) If you locked record one at the actual offset it would lock a range from byte 1001 to 1100. Any other station requesting READ or WRITE would be denied. Of course, we can read through locks in xBase, so how do they do it? The xBase languages add an arbitrary number to the actual offset. Originally, Clipper used 1,000,000,000 + record offset. Fox used another offset, and I am not sure but I think it was 4,000,000,000. We'll call this huge number the Lock Offset. Later, Clipper changed the Lock Offset to the same as Fox for certain RDD's. (.CDX and .IDX) For years, even though Clipper could create .NDX indexes, it was not Lock Offset compatible with dBase, and using both platforms on the same data caused incorrect locking. The Lock Offset numbers are arbitrarily large to keep actual data files from crossing the limit. (hopefully, we aren't creating any 1 trillion byte files) (or 4 trillion for newer schemes) So, in an xBase file, record locks and writes are at Lock Offset + File Offset and reads are at File Offset, so they do not run into a lock. This allows "read through" Locks between xBase systems are only able to be used concurrently when the arbitrary Lock Offset is the same in both systems. So, in the above example, to lock the first record the Lock Offset would be 4,000,001,001 to 4,000,001,100. If both languages used the same offset, then the write lock would be correctly enforced. _________________________________________________________________ These offsets are mentioned in online documentation (for CA-Clipper) (read 52eint.txt or clip53a.txt). The 1,000,000+RECNO() is used as default. If you want to use offset 4,000,000 you have to link the ntxlock2.obj file. For CDX indexes you should link cdxlock.obj to be compatible with Fox locking scheme (but only for Clipper != 5.2e) Confirmed by: r(ycho)GLAB, VIP Software (rglab@waw.pdi.net) SoftC uses 0x4,000,000L for lock offset in FoxPro files _________________________________________________________________ For more information on record locking read : "Transactional Locking, Part 1" by Thomas Wang (wang@cup.hp.com) on http://www.concentric.net/~Ttwang/tech/locks1.htm _________________________________________________________________ How do I cope with the Year 2000 problem ? In the header the date has the format YYMMDD which gives us the wonderful Year 2000 problem. Or does it ? The 1st of february 1997 is written in the header as: 61h 02h 01h. If your computer can handle date *after* the year 1999 you'll find that, the 1st of february 2001 is written in the header as: 64h 02h 01h. This means that the valid range for the year in the "last updated at" field in the dbf header is year 1900 - 2155 (value 00h to FFh + base year 1900). All other fields containing dates has the format YYYYMMDD, which can handle all valid dates (so far :-) Conclusion: Unless you care about data handling *after* the year 2155, the Xbase file formate should not impose any problems. _________________________________________________________________ Check out: "New Year 2000 page on The Oasis" by Phil Barnett: _________________________________________________________________ _________________________________________________________________ dBASE II FILES The Structure of dBASE II data files (*.dbf) _______________________ _______ 0 | Version number *1| ^ |-----------------------| | 1 | Number of records | Record 2 | in data file (16 bit) | header |-----------------------| | _ |=======================| _______ 3 | Date of last update | | / 0| Field name in ASCII | ^ 4 | YYMMDD | | / : (terminated by 00h) : | 5 | | | | | | | |-----------------------| | | 10| | | 6 | Length of each record | | | |-----------------------| For 7 | ( 16 bits ) *2| | | 11| Field type in ASCII *4| each |-----------------------|--|--- | |-----------------------| field 8 | | | ^ | 12| Field length (binary)| | 9 | Field descriptor | | | ____/ |-----------------------| | : Array *5 : | | 13| Field adress in memory| | : (Terminated by 0Dh) : | | 14| | | : : | | ______ |-----------------------| | : : | | \ 15| Field decimal count | | : : | | \_ |=======================| _v_____ | | | | 519| | | | |-----------------------| | | 520| Terminator *3|__v__v_ |=======================| | 521| Records | | : : | : : | : : | : : | n| | | |__End_of_File__________| ___v____ End of file ( 1Ah ) *11 *1 dBASE II version no: 02h *2 Sum of lengths of all fields + 1 (deletion flag). Max. length is 1,000 bytes *3 0Dh if all 32 fields present, otherwise 00h. *4 Field type: C, N or L *5 Max. 32 fields _________________________________________________________________ The Structure of dBASE II index file This was previously presented as the structure of dBASE III index files. Checking with the actual header of an index made it obvious, that it did NOT fit with dBASE III index files ( In that case several of the most essential key fields should be NULL values ). _______________________ _______ 0 | (Reserved) | ^ 1 | | | |-----------------------| | 2 | Node number of | | 3 | root node | | |-----------------------| | 4 | Node number of | Anchor 5 | next available node | node |-----------------------| description 6 | Length of key *1 | | |-----------------------| | 7 | Size of key entry *2 | | |-----------------------| | 8 | Maximum keys/node *3 | | |-----------------------| | 9 | Field type | | |-----------------------| | 10| Key expression in | | | ASCII | | : : | : : | | | | 109| (00h terminated) | | |-----------------------| | 110| (Unused) | | | | | _ : : | / |=======================| : : | / 0| Pointer to lower level| | | | / 1| (next page) | 511| ( 16 bits ) | | / |-----------------------| |=======================| _v_____ / 2| Record number | 0| No.of keys in node | ^ / 3| | |-----------------------| _|_____/ |-----------------------| 1| Array of key entries | | 4| Key expression | | | Index | | | | record : : |-----------------------| _|_____ : : : : | \ N| | 511| | | \______ |=======================| |=======================| _v_____ *1 Key length in bytes + 2 *2 Bytes in key expression + 2 *3 00h Character field (else) Numeric field _________________________________________________________________ The Structure of dBASE II Memory Files (*.mem) _______________________ _______ 0 | | ^ 1 | Variable name | | : terminated by 00h : Header : : | 9 | | | 10 | | | |-----------------------| | 11 | Variable type *1 | | |-----------------------| | 12 | Length of stored value| | |-----------------------| | 13 | ( Reserved ) | | 14 | | | |-----------------------| | 15 | Field length (binary)| | *2 |-----------------------| | 16 | Decimal count (binary)| | |-----------------------| | 17 | ( Reserved ) 00h | | 18 | ( Reserved ) 00h | | |-----------------------| | 19 | Value of variable | | : *3 : | : : | : : | : :__V_____ N |=======================| *1 C3h Character variable CEh Numerical variable CCh Logical variable *2 "E" marks the start of a definition *3 Text entries might have leading 00h, if text is shorter than field Logical 17 bytes are reserved, but only the last byte is used for 00h (false) or 01h (true). End-of-File Valid end of file (i.e. end of data) is indicated by 1Ah. _________________________________________________________________ _________________________________________________________________ Examples Description of test.dbf Name of data file : test.dbf Version no. : 5 Memo file present : 131 No. of records : 3 Length of header : 193 Length of records : 279 Date for latest change : 19960814 No. of fields : 5 Current record : 0 Crypted : no mdx/cdx file : no broken transaction : no Multi user information : 00 00 00 00 00 00 00 00 00 00 00 00 00 Field descriptions : Name Type length Decimal # ID N 5 0 # MSG C 254 0 # NOTE M 10 0 # BOOLEAN L 1 0 # DATES D 8 0 Description of test.ndx A index made on ID field in test.dbf Description of test.dbt A memo file containing the NOTE field from test.dbf _________________________________________________________________ Offset 0 1 2 3 4 5 6 7 8 9 A B C D E F 000000 83600811 03000000 C1001701 00000000 .`.............. ^^------ !!!!!!!! 000010 00000000 00000000 00000000 00000000 ................ 000020 49440000 00000000 0000004E 0700DA3F ID.........N...? 000030 05000000 01000000 00000000 00000000 ................ 000040 4D534700 00000000 00000043 0C00DA3F MSG........C...? 000050 FE000000 01000000 00000000 00000000 ................ 000060 4E4F5445 00000000 0000004D 0A01DA3F NOTE.......M...? 000070 0A000000 01000000 00000000 00000000 ................ 000080 424F4F4C 45414E00 0000004C 1401DA3F BOOLEAN....L...? 000090 01000000 01000000 00000000 00000000 ................ 0000A0 44415445 53000000 00000044 1501DA3F DATES......D...? 0000B0 08000000 01000000 00000000 00000000 ................ 0000C0 0D202020 20203152 65636F72 64206E6F . 1Record no 0000D0 20312020 20202020 20202020 20202020 1 0000E0 20202020 20202020 20202020 20202020 0000F0 20202020 20202020 20202020 20202020 000100 20202020 20202020 20202020 20202020 000110 20202020 20202020 20202020 20202020 000120 20202020 20202020 20202020 20202020 000130 20202020 20202020 20202020 20202020 000140 20202020 20202020 20202020 20202020 000150 20202020 20202020 20202020 20202020 000160 20202020 20202020 20202020 20202020 000170 20202020 20202020 20202020 20202020 000180 20202020 20202020 20202020 20202020 000190 20202020 20202020 20202020 20202020 0001A0 20202020 20202020 20202020 20202020 0001B0 20202020 20202020 20202020 20202020 0001C0 20202020 20202020 20202020 20203120 1 0001D0 31393936 30383133 2A202020 20324E6F 19960813* 2No 0001E0 20322020 20202020 20202020 20202020 2 0001F0 20202020 20202020 20202020 20202020 000200 20202020 20202020 20202020 20202020 000210 20202020 20202020 20202020 20202020 000220 20202020 20202020 20202020 20202020 000230 20202020 20202020 20202020 20202020 000240 20202020 20202020 20202020 20202020 000250 20202020 20202020 20202020 20202020 000260 20202020 20202020 20202020 20202020 000270 20202020 20202020 20202020 20202020 000280 20202020 20202020 20202020 20202020 000290 20202020 20202020 20202020 20202020 0002A0 20202020 20202020 20202020 20202020 0002B0 20202020 20202020 20202020 20202020 0002C0 20202020 20202020 20202020 20202020 0002D0 20202020 20202020 20202020 20202020 0002E0 20202020 20325931 39393630 38313420 2Y19960814 0002F0 20202020 334D6573 73616765 206E6F20 3Message no 000300 33202020 20202020 20202020 20202020 3 000310 20202020 20202020 20202020 20202020 000320 20202020 20202020 20202020 20202020 000330 20202020 20202020 20202020 20202020 000340 20202020 20202020 20202020 20202020 000350 20202020 20202020 20202020 20202020 000360 20202020 20202020 20202020 20202020 000370 20202020 20202020 20202020 20202020 000380 20202020 20202020 20202020 20202020 000390 20202020 20202020 20202020 20202020 0003A0 20202020 20202020 20202020 20202020 0003B0 20202020 20202020 20202020 20202020 0003C0 20202020 20202020 20202020 20202020 0003D0 20202020 20202020 20202020 20202020 0003E0 20202020 20202020 20202020 20202020 0003F0 20202020 20202020 20202020 334E3139 3N19 000400 39363031 30321A 960102. _________________________________________________________________ Hex dump of test.ndx 000000 01000000 02000000 00000000 08001F00 ................ 000010 01001000 00000000 49442000 80028403 ........ID ..... 000020 31002B00 03000100 03000100 01000100 1.+............. 000030 01000100 01000100 01000100 01000100 ................ 000040 01000100 01000100 01000100 01000100 ................ 000050 01000100 01000100 01000100 01000100 ................ 000060 01000100 01000100 01000100 01000100 ................ 000070 01000100 01000100 01000100 01000100 ................ 000080 01000100 01000100 01000100 01000100 ................ 000090 01000100 01000100 01000100 01000100 ................ 0000A0 01000100 01000100 01000100 01000100 ................ 0000B0 01000100 01000100 01000100 01000100 ................ 0000C0 01000100 01000100 01000100 01000100 ................ 0000D0 01000100 01000100 01000100 01000100 ................ 0000E0 01000100 01000100 01000100 01000100 ................ 0000F0 01000100 01D3EA03 DABA5800 03D03BDA ..........X...;. 000100 770CB8FE FFA20E69 5F5E8BE5 5DCB33DB w......i_^..].3. 000110 8EC3B452 CD218CC0 0BC37410 268E47FE ...R.!....t.&.G. 000120 26803E00 004D7504 8C060069 8E060269 &.>..Mu....i...i 000130 8CC1268B 1E010026 8B160300 83EA58BE ..&....&......X. 000140 00008B3E 0669A100 69C70600 6900008E ...>.i..i...i... 000150 C03BC174 153BC774 1C263B1E 01007515 .;.t.;.t.&;...u. 000160 4626A103 00050200 03D0833E 00690075 F&.........>.i.u 000170 048C0600 6926803E 00004D75 0A8CC026 ....i&.>..Mu...& 000180 03060300 40EBC889 56FE8936 0C69F746 ....@...V..6.i.F 000190 06100075 6AF74606 0100745C 1EB067B4 ...uj.F...t\..g. 0001A0 35CD218C C88ED8BE 15A5BF0A 00B90800 5.!............. 0001B0 F3A61F75 43B440CD 670AE475 3BB446CD ...uC.@.g..u;.F. 0001C0 670AE475 33C86F7C 26D632D6 326A01A5 g..u3.o|&.2.2j.. 0001D0 3420007C 26E4326C 10881411 346431F0 4 .|&.2l....4d1. 0001E0 32643104 00FA3340 07881415 34643133 2d1...3@....4d13 0001F0 003000EB 3F494400 F7460610 00754BF7 .0..?ID..F...uK. 000200 03000000 00000000 01000000 00000000 ................ 000210 0000F03F 00000000 02000000 00000000 ...?............ 000220 00000040 00000000 03000000 00000000 ...@............ 000230 00000840 00000000 5F03C102 5F035101 ...@...._..._.Q. 000240 7B007C00 7D005101 6C036D03 57026E03 {.|.}.Q.l.m.W.n. 000250 AE025702 54025101 A7025101 FB015900 ..W.T.Q...Q...Y. 000260 31005101 0C025D03 5101C302 C402C502 1.Q...].Q....... 000270 C602C702 C802C902 CA025101 C5010802 ..........Q..... 000280 AE034201 9B000902 2F02DA00 0A02FD02 ..B...../....... 000290 06000800 09000A00 0B000C00 0D000E00 ................ 0002A0 0F000700 AB00AD00 AE00AF00 B000B100 ................ 0002B0 B200B300 B400AC00 C5011F03 51014201 ............Q.B. 0002C0 5101DD01 5101DA00 5101FD02 C5015101 Q...Q...Q.....Q. 0002D0 51014201 51015101 51015101 5101FD02 Q.B.Q.Q.Q.Q.Q... 0002E0 51015101 51015101 51015101 43035101 Q.Q.Q.Q.Q.Q.C.Q. 0002F0 5101FD02 D2025F03 DC025F03 E0025F03 Q....._..._..._. 000300 DB025F03 DF025F03 DD025F03 DE025F03 .._..._..._..._. 000310 5702E102 57025402 51015602 E202D302 W...W.T.Q.V..... 000320 5201D402 AE02AF02 B002B102 B202B302 R............... 000330 52015402 51015E00 5F006000 61005101 R.T.Q.^._.`.a.Q. 000340 5602D502 D3025201 D802D902 5201DA02 V.....R.....R... 000350 AF02B002 52015702 54025101 CB02CC02 ....R.W.T.Q..... 000360 CD02CE02 CF02D002 51015602 AD02AE02 ........Q.V..... 000370 AF02B002 B102B202 54025702 51015602 ........T.W.Q.V. 000380 D602D302 5201AE02 D7025402 57025101 ....R.....T.W.Q. 000390 80023100 51018002 84033100 51018002 ..1.Q.....1.Q... 0003A0 31005101 11015F03 51014800 49005101 1.Q..._.Q.H.I.Q. 0003B0 A600C102 51014C03 31005101 4C038602 ....Q.L.1.Q.L... 0003C0 31005101 56021B00 54021D00 56025201 1.Q.V...T...V.R. 0003D0 5F031C00 51025602 AE02AF02 5802B002 _...Q.V.....X... 0003E0 B1025002 52015702 54025101 50025402 ..P.R.W.T.Q.P.T. 0003F0 1E001F00 51022000 5602B102 B302B502 ....Q. .V....... _________________________________________________________________ Hex dump of test.dbt *1 *2 vvvvvvvv vvvvvvvv 000000 04000000 8701021D 03000002 5E126431 ............^.d1 000010 03000000 00000300 00008701 021D0300 ................ \ 000020 00025E12 64310300 00000000 02000000 ..^.d1.......... | 000030 8701021D 03000002 5E126431 03000000 ........^.d1.... | 000040 00000100 00006572 69632020 44617465 ......eric Date | 000050 20202020 204C6F67 6963616C 20204D65 Logical Me | 000060 6D6F2020 20202000 FF7604E8 26CF83C4 mo ..v..&... | 000070 0C5E5FC9 C3908B76 048B4606 50568976 .^_....v..F.PV.v | 000080 EA8946EC 900EE855 9B83C404 C45EEA2A ..F....U.....^.* | 000090 E4268A47 24C45E0A 268907C4 5EEA268A .&.G$.^.&...^.&. | Header 0000A0 47048E46 10268905 C45EEA26 F6471610 G..F.&...^.&.G.. | (mostly 0000B0 7503E9A3 00C45E0A 26832F02 5E5FC9C3 u.....^.&./.^_.. | garbage) 0000C0 6A01EB9A 16261F11 1F110300 C1009219 j....&.......... | 0000D0 00B8D80A BE197C26 16262411 24110300 ......|&.&$.$... | 0000E0 D500A619 00B8E20A D2197C26 BF186DD0 ..........|&..m. | 0000F0 0670A107 A1080672 CC026431 7C26BA19 .p.....r..d1|&.. | 000100 DC01CC19 D2196431 2F001100 21002F00 ......d1/...!./. | 000110 6D00D21A 0318CC19 21000300 D2196431 m.......!.....d1 | 000120 11002100 1E1B6431 03002020 20006163 ..!...d1.. .ac | 000130 74657200 5E5FC9C3 8B760023 2300268A ter.^_...v.##.&. | 000140 44032AE4 8CC1C45E 0A268907 8EC1268A D.*....^.&....&. | 000150 44028E46 10268905 5E5FC9C3 C8060000 D..F.&..^_...... | 000160 57568B4E 108B7E14 32C0F406 F10A1200 WV.N..~.2....... | 000170 F10A4400 8E1A3C1A F6006C22 08000F00 ..D...<...l".... | 000180 07000002 0A00246F 0A02DE13 D0367C26 ......$o.....6|& | 000190 2E018221 06727C26 0814820A F10A0700 ...!.r|&........ | 0001A0 0A00D036 00020A00 D0360000 00020700 ...6.....6...... | 0001B0 00060000 0000D136 2C14E707 F10A0F00 .......6,....... | 0001C0 10001900 D036726D 7C260000 07000000 .....6rm|&...... | 0001D0 00008C6D 08002A14 00007C26 9A018221 ...m..*...|&...! | 0001E0 46727C26 4614CB00 F10A0700 00000000 Fr|&F........... | 0001F0 00000700 0F060000 00008C6D 7C264E14 ...........m|&N. / 000200 54686973 20697320 61206D65 6D6F2066 This is a memo f \ <- 000210 6F726520 7265636F 7264206E 6F206F6E ore record no on | | *3 000220 651A1A11 C4D92E20 4C656176 65206D65 e...... Leave me |<- 000230 6E75202D 201B1A2E 20426C61 636B626F nu - ... Blackbo | 000240 61726420 2D204631 302E0052 616E6765 ard - F10..Range | 000250 2076616C 7565206D 75737420 6265206E value must be n | 000260 756D6572 69632E20 20507265 73732061 umeric. Press a | 000270 6E79206B 65792074 6F20636F 6E74696E ny key to contin | 000280 75652E00 2500EA08 00AA209A D0027F1D ue..%..... ..... | 000290 2400EA00 00911F9A D0027F1D 1100EA00 $............... | 0002A0 00451E9A D0027F1D 0800EA14 08D21D9A .E.............. | 0002B0 D0027F1D 1000EA00 00451E9A D0027F1D .........E...... | 0002C0 1900EA00 00D21D9A D0027F1D 0C00EA00 ................ | 0002D0 00D21D9A D0027F1D 1800EA00 00D21D9A ................ | 0002E0 D0027F1D 0A00EA00 00D21D9A D0027F1D ................ | 0002F0 1300EA00 0068219A D0027F1D 1200EA00 .....h!......... | 000300 0068219A D0027F1D 1400EA00 0068219A .h!..........h!. | 000310 D0027F1D 1600EA00 0068219A D0027F1D .........h!..... | 000320 1600EA05 0368219A D0027F1D 1500EA00 .....h!......... | 000330 0068219A D0027F1D 1200EA24 0968219A .h!........$.h!. | 000340 D0027F1D 1200EAC8 0E68219A D0027F1D .........h!..... | 000350 1200EA82 1268219A D0027F1D 1200EABD .....h!......... | 000360 0168219A D0027F1D 1200EAA8 1468219A .h!..........h!. | 000370 D0027F1D 1200EA7D 0068219A D0027F1D .......}.h!..... | 000380 1200EA3D 0068219A D0027F1D 1200EAB2 ...=.h!......... | 000390 0068219A D0027F1D 1200EA1A 0D68219A .h!..........h!. | 0003A0 D0027F1D 1200EAE3 1268219A D0027F1D .........h!..... | 0003B0 1200EA44 1368219A D0027F1D 2400EA35 ...D.h!.....$..5 | 0003C0 09911F9A D0027F1D 2400EA4F 0B911F9A ........$..O.... | 0003D0 D0027F1D 2400EA56 1E911F9A D0027F1D ....$..V........ | 0003E0 2400EAC7 1E911F00 00000000 00000000 $............... | 0003F0 BE000026 8B8C0400 41742E26 8B940800 ...&....At.&.... _| 000400 54686973 20697320 6D656D6F 20666F72 This is memo for \ <- Second 000410 20726563 6F726420 321A1A1C 00040000 record 2....... |<- entry 000420 E54F5445 30332020 4E445800 00000000 .OTE03 NDX..... | 000430 00000000 00002099 8C1F8945 00040000 ...... ....E.... | 000440 E54F5445 30202020 44425400 00000000 .OTE0 DBT..... | 000450 00000000 00009C94 821F9345 00040000 ...........E.... | 000460 E54F5445 30202020 44424600 00000000 .OTE0 DBF..... | Second 000470 00000000 00009C94 821F9445 28020000 ...........E(... | block 000480 E54F5445 30342020 4E445800 00000000 .OTE04 NDX..... | 000490 00000000 00002232 8D1F6E1C 00040000 ......"2..n..... | 0004A0 E5455820 20202020 20202000 00000000 .EX ..... | 0004B0 00000000 00004C32 8D1F8A45 FD2F0000 ......L2...E./.. | 0004C0 E545447B 45442020 45444320 00000000 .ED{ED EDC .... | 0004D0 00000000 00008532 8D1F0000 00000000 .......2........ | 0004E0 E545447B 45443120 45445420 00000000 .ED{ED1 EDT .... | 0004F0 00000000 00008532 8D1F0000 00000000 .......2........ | 000500 E545447B 45443120 45444220 00000000 .ED{ED1 EDB .... | 000510 00000000 00008532 8D1F0000 00000000 .......2........ | 000520 E545447B 45442020 45445320 00000000 .ED{ED EDS .... | 000530 00000000 00008532 8D1F8D45 00100000 .......2...E.... | 000540 00000000 00000000 00000000 00000000 ................ | 000550 00000000 00000000 00000000 00000000 ................ | 000560 00000000 00000000 00000000 00000000 ................ | 000570 00000000 00000000 00000000 00000000 ................ | 000580 00000000 00000000 00000000 00000000 ................ | 000590 00000000 00000000 00000000 00000000 ................ | 0005A0 00000000 00000000 00000000 00000000 ................ | 0005B0 00000000 00000000 00000000 00000000 ................ | 0005C0 00000000 00000000 00000000 00000000 ................ | 0005D0 00000000 00000000 00000000 00000000 ................ | 0005E0 00000000 00000000 00000000 00000000 ................ | 0005F0 00000000 00000000 00000000 00000000 ................ _| 000600 54686973 20697320 6D656D6F 20331A1A This is memo 3.. <- 3rd entry *4 ) *1) First 4 bytes indicates no. of next free block *2) (FoxBase) Size of blocks. This is a dBASE III+ file and byte 4-511 is just garbage. *3) First entry (terminated by 1Ah 1Ah) *4) NOTE! Last entry is NOT a complete block. dBASE does not write the full block to the memo file. The block contains the memo + terminator (1Ah 1Ah) _________________________________________________________________ dBASE Specifications dBASE II dBASE III dBASE IV Max. no. of records 65,535 1,000,000,000 1,000,000,000 Max. fields per record 32 128 255 Max. data files open 10 10 Max. index files per open database 7 47 Max. record size in bytes 1,000 4,000 4000 Max. records per file 65,535 Max. bytes per file 8,000,000 Max. memory variables - 256 Max. memory for variables - 6,000 bytes *3 No. of data types 5 6 Max. size of MEMO file 5000 bytes 64000 bytes Max. character field size in bytes 254 254 254 Max. numerical field size in bytes 19 20 Size of logical field 1 byte 1 byte 1 byte Size of date field 8 bytes 8 bytes Size of memo pointer in DBF - 10 bytes Size of floating point - 1-2 *3 Can be expanded to 31 KB using CONFIG, 6 KB is mentioned as default. _________________________________________________________________ _________________________________________________________________ dBASE versions Source: Romain Strieff [dBVIPS] in article in newgroup comp.databases.xbase.misc. dBASE II VERSION RELEASED COMMENTS 2.02 1980 First vers - 8 bit 2.02a 2.2 2.3 Jan 82 2.3a Jun 82 2.3b Aug 82 First 16 bit (quite buggy) 2.3c Internal release only 2.3d STABLE 16 bit version 2.4 Apr 83 2.41 Feb 84 2.43 Jan 85 2.43* Jun 85 *ONLY* version to utilize DOS 3.x dBASE III 1.0 Jun 84 Copy protected 1.0e /TR> 1.1 Nov 84 1.2 Oct 85 dBASE III PLUS 1.0 x77 Dec 85 1.0 x95c May 86 1.1 x100 Aug 86 NO Copy protection 1.1 x102 Jan 87 dBASE IV ? ? dBASE 5 for DOS ? ? dBASE 5 for Windows ? ? Visual dBASE 7 ? ? _________________________________________________________________ List of File extensions .$$$ temporary file (dBASE III) .$db temporary file (dBASE IV) .act FoxDoc Action Diagrams (FoxPro) .app application object file (dBASE Application Generator) .app generated application (FoxPro) .bak Backup file (dBASE ) .bar horizontal bar menu object file (dBASE Application Generator) .bin Binary files (dBASE) .bch batch process object file (dBASE Application Generator) .cac dBASE IV executable when caching on/off (see cachedb.bat) .cat catalog (dBASE IV) .cdx compound index (FoxPro) .ch header file (Clipper 5) .cht interface file for ChartMaster (dBASE) .clp compiler script file (clip list) (Clipper 5) .cmd command (dBASE - Waffle) .cod template source file (dBASE Application Generator) .cpt encrypted memo file (dBASE) .crp encrypted database (dBASE IV) .ctl control file (dBASE IV - Aldus Setup) .cvt backup file for CONVERTed database file (dBASE IV) .db configuration (dBASE IV - dBFast) .db$ temporary file (dBASE) .db2 database (dBASE II) .db3 database (dBASE III) .dbf database file (dBASE III/IV - FoxPro - dBFast - DataBoss) .dbk database backup (dBASE IV) .dbo compiled program (dBASE IV) .dbt FoxBASE+ style memo (FoxPro) .dbt memo file for database w/same name (dBASE IV - dBFast) .def Definitions list (dBASE) .dif Data Interchange Format or VisiCal file. Used with APPEND FROM and COPY (dBASE) .doc Documentation text file (dBASE Application Generator) .fil files list object file (dBASE Application Generator) .fky macro file (FoxPro) .fmo compiled format file (dBASE IV) .fmt format file (dBASE IV - FoxPro - Clipper 5 - dBFast) .fp configuration file (FoxPro) .fpc catalog (FoxPro) .fpt memo (FoxPro) .fr3 renamed dBASE III+ form file (dBASE IV) .frg uncompiled report file (dBASE IV) .frm report file (dBASE IV - Clipper 5 - dBFast) .fro compiled report file (dBASE IV) .frt report memo (FoxPro) .frx report (FoxPro) .fw2 Framework spreadsheet or database file (Framework - dBASE) .fxp compiled format (FoxPro) .gen compiled template (dBASE Application Generator) .idx index (many - FoxPro) .ind include index (dBASE IV) .inx index (Foxbase) .key Key macro library (dBASE) .lbg label generator data (dBASE IV) .lbl label (dBASE IV - Clipper 5 - dBFast) .lbo compiled label (dBASE IV) .lbt label memo (FoxPro) .lbx label (FoxPro) .ld1 overlay file (dBASE) .log Transaction log file (dBASE) .mbk multiple index file backup (dBASE IV) .mdx multiple index file (dBASE IV) .mem memory variable save file (dBASE IV - FoxPro) .mnt menu memo (FoxPro) .mnx menu (FoxPro) .mpr generated program (FoxPro) .mpx compiled menu program (FoxPro) .ndx index file (dBASE II - III - IV - dBFast) .npi source for DGEN.EXE intepreter (dBASE Application Generator) .ntx index file (Clipper 5) .pjt project memo (FoxPro) .pjx project (FoxPro) .plb library (FoxPro) .pll pre-linked library (Clipper 5) .plt pre-linked transfer file (Clipper 5) .pop pop-up menu object (dBASE Application Generator) .ppo pre-processor output (Clipper 5) .pr2 printer driver (dBASE IV) .pr3 PostScript printer driver (dBASE IV) .prf printer driver (dBASE IV) .prg program source (dBASE IV - FoxPro - Clipper 5 - dBFast) .prs procedure (dBASE IV) .prt Print dump (dBASE) .prx compiled program (FoxPro) .qbe saved query (Query By Example) (dBASE IV - Quattro Pro) .qbo compiled query (dBASE IV) .qpr generated query program (FoxPro) .qpx compiled query program (FoxPro) .qry query (dBASE IV) .res dBASE resources (dBASE IV) .rpd Rapid file. Used for IMPORT/EXPORT and from APPEND, FROM and COPY (dBASE) .sc3 renamed dBASE III screen mask file (dBASE IV) .scr screen - screen snapshot (dBASE IV - Procomm Plus) .sct screen memo (FoxPro) .scx screen (FoxPro) .spr genarated screen program (FoxPro) .spx compiled screen program (FoxPro) .str structure list object file (dBASE Application Generator) .t44 Temporary file for Sort or Index (dBASE IV) .tbk memo backup (dBASE IV - FoxPro) .tvf table view settings (dBASE) .upd update data (dBASE) .upo compiled update data (dBASE) .val values list object file (dBASE Application Generator) .vew view file (Clipper 5, Lotus Approach) .vue view (dBASE IV - FoxPro) .w44 temporary file for Sort or Index (dBASE) .wfm form object (dBASE Form Designer) .win window file (FoxPro - dBASE) _________________________________________________________________ HISTORY 2000-12-14 Added links and references: dbase.com 2000-11-10 Updated links and references: php 2000-07-05 Updated links and references 2000-06-04 Added a reference to tDbf. 2000-05-19 Updated a few references. 2000-01-17 Updated a few references. And a few misspellings corrected 1999-10-22 References added. And a few misspellings corrected 1999-07-30 dBASE version sceme. 1999-03-08 Minor additions. 1998-11-28 Updating some links. 1998-09-21 The path to CxBase : A Perl Library for manipulating Xbase files fixed: http://www.e-bachmann.dk/archive/cxbase.zip 1998-08-26 More references. 1998-08-24 More references (Perl). List of File extentions. 1998-07-16 FoxPro/FoxBase specific notes. 1998-04-07 More references. Java and Rexx. 1998-03-26 New references. 1998-03-03 A reference to a Perl Xbase manipulation library added. 1997-09-29 A reference to a Perl Xbase manipulation library added. 1997-09-17 Fixing minor bug in reference list Reference list: Pratap Pereira moved to new host 1997-08-11 Updating structure of: data file (*.dbf): codepages etc. Memo files (*.dbt): dBASE III & dBASE IV does *not* use the same structure Memory files (*.mem): Full structure of file Clipper Index (*.NTX): Page structure added. Header structure improved dBASE II data and index file Adding structure of: Fox Pro object and memo files (*.fpt) dBASEII Memory files (*.mem) dBASE IV Multple index files (*.MDX) 1997-06-02 Fixing bug in calculating dates for "The Year 2000": 1900 + 255 = 2155 1997-04-16 Note on Year 2000 problems. Correcting page description in index file .ndx. 1997-04-18 Added the chapter: The Structure of Compound Index files (*.cdx) by David Kuechler 1997-03-10 Still more references and updates of references. Refining description of NTX file. 1997-01-27 Description of .MEM (Memory index file) and .NTX (Clipper Index File). Description of Database Container in Visual FoxPro More references and various minor changes in text. 1997-01-09 Description of .MDX (Multiple index file) - This seems to be a mistake :-( 1996-11-27 Document converted to HTML 1996-11-19 Minor fixes: Elements in Field Descriptor Array are exact 32 B long. Typing error in data type Float. "What to check on opening a .DBF file" added. 1996-10-18 Chapter on read/write locks using share by Phil Barnett (midnight@the-oasis) 1996-10-15 Change in description of structure of index files. Major mistake! The previous version described the structure for dBASE II index files. Only excuse: This mistake was made by several of my sources :-( 1996-10-03 First public version of this document (as far as I remember :-) _________________________________________________________________ REFERENCE LIST These references describe, where I found the documents - not where they are now. If you find dead links - please keep me informed. 1. Bachmann, Erik: Xbase : File format description / Erik Bachmann. - Roskilde, Denmark : Clickety Click Software, 1996-1998. - aprox. 38 pg. ; ASCII text file / HTML document URL: http://www.e-bachmann.dk/docs/xbase.html 2. Barnett, Phil: The Oasis is a Clipper Programmers Source Code Archive / Phil Barnett. Abstract: The Oasis is the largest and best maintained file archive for CA-Clipper and xBase on the web, and is still growing! The Oasis is created specifically for Clipper programmers to satisfy their need for demo's, utilities, Clipper source code, patches and libraries. The Oasis evolved from the FIDO filebone, additions from FIDO message bases, messages from the internet comp.lang.clipper newsgroup, my personal source code and utility donations and other programmers donations directly into the site. URL: http://www.the-oasis.net/ 3. Born, Günter: The File Formats Handbook / Günter Born. - London : Thomson, 1995. - 1274 pg. - ISBN 1-85032-117-5 4. CA-Clipper File Structures : Detailed Structure Information. . - ( Xbase Techniques. ; Computer Associates International, Inc. ). - 1993. - Pg. 7-10 5. Botstein, Boris: DbfNtx / Boris Botstein DbfNtx provide some classes and routines to develop applications for quick access CA-Clipper's 5.01 tables & indices. URL: http://www.simtel.net/pub/simtelnet/win95/prog/dbfntx01.zip Reference from: Ben Engbers 6. Castro, L.: Advanced programmer's guide featuring dBASE III and dBASE II / L. Castro. - Culver City, California, USA : Ashton-Tate, 1985. - 10+664 pg. - ISBN 0-912677-05-8 Note: Literature list and Terminology list 7. dBASE .DBF File Structure. - (Borland Technical Documents ; TI12821) URL: http://loki.borland.com/winbin/bds.exe?getdoc+2821+Delphi 8. dBASE .DBF File Structure Data File Header Structure for the dBASE Version 7 Table File. - 44k URL: www.dbase.com/KnowledgeBase/int/db7_file_fmt.htm 9. Dechert, Alan Fixing dBASE DOS applications for Year 2000 Compliance URL: http://members.aol.com/adechert/y2kscan.htm 10. Eacker, Brad: DBF : A set of tools and library routines to manipulate xbase files / Brad Eacker : Silicon Graphics, 1994. - Computer files ; C source ; ASCII text Note: UUNET vol. 43 1994 Abstract: UUnet : volume43 (Period: 08 Jun 94 - 24 Jul 94), dbf/part0[1-2] : dbf - xbase manipulation package URL: ftp://ftp.uu.net/usenet/comp.sources.misc/volume43/dbf/part01.Z URL: ftp://ftp.uu.net/usenet/comp.sources.misc/volume43/dbf/part02.Z 11. Err : "Not a Database File". - (Microsoft Knowledge Base. ; Article Q98743) URL: http://support.microsoft.com/support/kb/articles/q98/7/43.asp 12. Ganaye, Pascal: TDbf - a Delphi component. Abstract: TDbf is a TTable like component for single-user application. It allow you to use DBF tables in your small delphi project with no need of any big dll and without to have to install the BDE. URL: http://tdbf.netfirms.com 13. General Format of .dbf files in Xbase Language. - (Multisoft GmbH ; 1996) URL: http://www.fship.com/pub/multisoft/flagship/docu/dbfspecs.txt 14. Gmelch, Rasca: libdbf : simple routines for accessing xbase data files / Rasca Gmelch. - Berlin, 1996. - Computer files ; C source ; ASCII text URL: URL: http://home.pages.de/~rasca/dbflib/ NOTE: This homepage has moved lately and might not be active at the moment 15. Hogan, T.: The Programmers's PC sourcebook : Reference tables for IBM PCs and compatibles, PS/2 systems, EISA-based systems, MS-DOS operating system through version 5, Microsoft Windows through version 3 : Hundred of new charts and tables / T. Hogan. - Redmond, Washington, USA : Microsoft Press, 1991. - Multiple pagination. - ISBN 1-55615-321-X 16. Kunkel, Gary Xbase DBMS / Gary Kunkel This product provides C and C++ programmers a class and function library for manipulating Xbase type datafiles and indices. XBase DBMS currently includes routines to support multi-user access for .DBF databases, fields, Dbase IV memo fields (variable length fields), dates, record and file locking and indexes (.NDX). There is also an HTML user interface class which works well with the Apache Web Server. Future releases will support filters, enhanced .MDX index files, transaction support, Dbase III memo fields, a client server configuration, secure data options and other enhancements requesteed by anyone using this library. URL: http://www.startech.keller.tx.us/xbase/xbase.html 17. How to Modify the Table Header from FoxPro. - (Microsoft Knowledge Base. ; Article Q139758 ; ) URL: http://support.microsoft.com/support/kb/articles/q139/7/58.asp 18. OOxBase (Version 2.10) - A SOM Interface To dBase (OS/2) (BETA). - (American Coders, LTD.) URL: http://www.americancoders.com/ 19. Pazdziora, Jan DBD::XBase : Module for dealing with XBase files Package DBD::XBase contains module XBase that can read and write dbf and dbt file, and also alpha release of DBI driver, that will be further extended to support everything required by DBI 0.92. URL: http://www.fi.muni.cz/~adelton/perl/ Author Address: adelton@fi.muni.cz 20. Pereira, Pratap Xbase.pm v. 1.07 : a module for perl 5 Author Source: http://www.best.com/~pereira Author Address: pereira@best.com This module seems to be unsupported. Try: Jan Pazdziora's "Module for dealing with XBase files". 21. The PHP Documentation Group php Reference Manual / The PHP Documentation Group These functions allow you to access records stored in dBase-format (dbf) databases. URL: http://www.php.net/manual/ref.dbase.php Max for Linux PlugSys International LLC [http://www.plugsys.com] The new application development family that leverages the traditional strengths of Clipper and Xbase while exploiting the power of Linux and the memory management of 32-bit Windows. 22. RexxBase (Version 2.21) - The dBase Database For REXX. - (American Coders, LTD.) URL: http://www.americancoders.com/RexxBase.html 23. Seay, Doug: CxBase : A Perl Library for manipulating Xbase files / Doug Seay Author Source: CxBase.zip Author Address: seay@absyss.fr It seems to be unsupported :-) This package was former known as CodeBase, but the name was changed (by me) to CxBase due to a violation on Sequiters copyright on the name CodeBase. Simpson, Alan: dBASE III PLUS : Programmer's Reference Guide / Alan Simpson. - Almeda : Sybex Inc., 1987. - 1029 pg. - ISBN 0-89588-301-5 Abstract: Data file structure and memo file structure for xBase Spence, Rick: Clipper Programming Guide / Rick Spence. - 2.nd edition. - Microtrend Books, Slawson Communications, Inc. - ISBN 0-915391-41-4 Stevens, A.: Turbo C : Memory-resistent utilities, screen I/O and programming techniques / A. Stevens. - Portland, Origon, USA : MIS Press, 1987. - 10+315 pg. - ISBN 0-943518-35-0 Note: Video Windows and TSR utility programs Townsend, Carl: Mastering dBASE III : A Structured Approach / Carl Townsend. - Berkeley : Sybex Inc., 1985. - ISBN 0-89588-301-5 Abstract: Data file structure and index file structure for xBase Walden, J.: File formats for popular PC software : A programmer's reference / J. Walden. - New York, New York, USA : Wiley, 1986. - 16+287 pg. - ISBN 0-471-83671-0 WANG, Thomas: Transactional Locking, Part 1 / Thomas Wang (wang@cup.hp.com) URL: http://www.concentric.net/~Ttwang/tech/locks1.htm What FoxPro Checks When Opening a .DBF File. - (Microsoft Knowledge Base. ; Article Q119763) URL: http://support.microsoft.com/support/kb/articles/q119/7/63.asp It seems that Microsoft has removed that document. WHITE, Gary: Some dBASE Stuff / Gary White This is my dBASE stuff. It ranges from old stuff for the DOS versions of dBASE to new stuff for Visual dBASE version 7. There's even some stuff that's non-version-specific. You'll also find links to some other very good sites. Don't forget the FAQ (Frequently Asked Questions), which is included in a site search. URL: http://www.apptools.com/dbase/index.html White Paper on CodeBase 6, xBASE technology, and Sequiter's OLE DB development plan. - (Sequiter Software) URL: http://www.sequiter.com/papers/wpcbase6.htm xBaseJ - Java Objects To Read and Write to dBase Files. - (American Coders, LTD.) URL: http://www.americancoders.com/xBaseJ.html