DATAFLEX 2.3B DATAFILE HEADER STRUCTURE By Peter M. Grillo MAINSTREAM COMPUTER CONSULTING Following is the structure of the DataFlex .DAT file for 2.3. Data Access Corporation has deemed the structure of the .DAT file as proprietary. The following definition of a 2.3 .DAT file was derived independently by myself and any problem arising from the use of this information will be your problem. Please do not call DAC and snivel. Use at own risk. Please do not upload this to DAC's BBS. DAC has indicated to me that I can release this information providing I include the prior disclaimer. All that aside, this is everything I know about a DataFlex .DAT file. The overall layout of a 2.3 .DAT file is header, null record and data. The header contains information about the file definition. Just about everything you define in DFFILE can be found in the header except for tag names. It is possible to read the header of a 2.3 .DAT file and the corresponding .TAG file to produce a perfect .DEF file. The following show offsets into the header: (LSB = Least significant byte) (MSBT = Most significant bit) DECIMAL HEX DESCRIPTION 01 - 04 00 - 03 HIGHEST RECORD COUNT EVER (LSB FIRST) 09 - 12 08 - 0B RECORD COUNT (LSB FIRST) 13 - 16 0C - 0F MAXIMUM NUMBER OF RECORDS (LSB FIRST) 79 - 80 4E - 4F RECORD LENGTH (LSB FIRST) 89 58 DELETED SPACE (1=REUSED, 0=NOT REUSED) 90 59 NUMBER OF FIELDS 93 5C MULTIUSER REREAD (1=ACTIVE, 0=INACTIVE) 101 64 NUMBER OF FIELDS IN INDEX 1 (MSBT SET 1 IF BATCH) 102-108 65 - 6B FIELD SEGMENTS OF INDEX 1 109 6C NUMBER OF FIELDS IN INDEX 2 (MSBT SET 1 IF BATCH) 110-116 6D - 73 FIELD SEGMENTS OF INDEX 2 117 74 NUMBER OF FIELDS IN INDEX 3 (MSBT SET 1 IF BATCH) 118-124 75 - 7B FIELD SEGMENTS OF INDEX 3 125 7C NUMBER OF FIELDS IN INDEX 4 (MSBT SET 1 IF BATCH) 126-132 7D - 83 FIELD SEGMENTS OF INDEX 4 133 84 NUMBER OF FIELDS IN INDEX 5 (MSBT SET 1 IF BATCH) 134-140 85 - 8B FIELD SEGMENTS OF INDEX 5 141 8C NUMBER OF FIELDS IN INDEX 6 (MSBT SET 1 IF BATCH) 142-148 8D - 93 FIELD SEGMENTS OF INDEX 6 149 94 NUMBER OF FIELDS IN INDEX 7 (MSBT SET 1 IF BATCH) 150-156 95 - 9B FIELD SEGMENTS OF INDEX 7 157 9C NUMBER OF FIELDS IN INDEX 8 (MSBT SET 1 IF BATCH) 158-162 9D - A3 FIELD SEGMENTS OF INDEX 8 163 A4 NUMBER OF FIELDS IN INDEX 9 (MSBT SET 1 IF BATCH) 164-170 A5 - AB FIELD SEGMENTS OF INDEX 9 171 AC NUMBER OF FIELDS IN INDEX 10 (MSBT SET 1 IF BATCH) 172-108 AD - B3 FIELD SEGMENTS OF INDEX 10 181 -183 B4 - BC FILE ROOT NAME (NULL TERMINATED) START OF FIELD DEFINITIONS. REPEAT FOR EACH FIELD. 197-198 C4 - C5 FIELD OFFSET (LSB FIRST) 199 C6 MSBT=MAIN INDEX, LSBT=(DECIMAL POINTS/2) 200 C7 FIELD LENGTH 201 C8 FIELD TYPE 00=ASCII, 01=NUMERIC, 02=DATE, 03=OVERLAP 202 C9 RELATES TO FILE NUMBER 203-204 CA - CB RELATES TO FIELD NUMBER (LSB FIRST) ...-... .. - .. (REPEAT FOR EACH FIELD) The null record follows the header and usually contains 00h's. The number of bytes in the null record corresponds to the record length of the file. The null record is record number zero. The data that follows are records in order of record number. The number of bytes in each record corresponds to the record length. Records are grouped together by blocks of 512 bytes. Not every record length, however, divides evenly into 512 so you get the occurrence of fill bytes or 0FFh's to round out a group of records to 512 bytes. Consider the following: Record Length Layout 128 Divides into 512 evenly so no fill bytes are used 170 Divided by 512 is 3 with a remainder of 2 so after every 3 records (starting at record 0) the are 2 fill bytes (0FFh's) Here is a table of common record lengths: Record Length Records in 512 Group Number of Fill Bytes 256 2 0 170 3 2 128 4 0 102 5 2 85 6 2 73 7 1 64 8 0 56 9 8 51 10 2 46 11 6 42 12 8 39 13 5 36 14 8 34 15 2 32 16 0 30 17 2 28 18 8 26 19 18 25 20 12 24 21 8 23 22 6 22 23 6 21 24 8 20 25 12 19 26 18 18 28 8 17 30 2 16 32 0 15 34 2 14 36 8 13 39 5 12 42 8 11 46 6 10 51 2 9 56 8 8 64 0 > [fold] [ > [fold] [ Deleted records are filled with 00h's until reused. DataFlex .DAT files can be opened from .FLX files using DIRECT_INPUT. You can then use READ_BLOCK commands to read information. Reading the FILELIST.CFG file is also much more efficient using DIRECT_INPUT and READ_BLOCK. The first 128 bytes are fill and each successive block of 128 bytes is a file in the list. In other words, if you want file 15 then DIRECT_INPUT 'FILELIST.CFG' and READ_BLOCK off (15*128) bytes. This would point you to the block for file 15. From there you can read off bytes to find the Root Name, Description, and DataFlex Name using the following layout. > [fold] ] > [fold] ] DECIMAL HEX DESCRIPTION 01 - 41 00 - 28 FILE ROOT NAME (NULL TERMINATED) 42 - 74 29 - 49 FILE DESCRIPTION (NULL TERMINATED) 75 - 128 4A - 7F DATAFLEX FILE NAME (NULL TERMINATED) > [fold] 2