_______________________ _______
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
- dBASE II version no:
02h
- Sum of lengths of
all fields
+ 1 (deletion flag). Max. length is 1,000
bytes
- Terminator:
0Dh if all 32 fields present, otherwise 00h.
- Field type
Field type: C, N or L
- Field descriptor array
Max. 32 fields
- Field lenght:
0 - ffh. Logical fields = 1, decimal no ( = no of
digits)-
- Field name
can
be undefined (= 1 x 00h)
- Field address in memory
can be ignored.
- Deleted flag
.
Blanks (20h) are valid! "*" = deleted.
Note tha records remain in the datafile when deleted (i.e. are marked
with "*")
The deleted record are moved out of the valid range of recors by
the pack command. But is still pressent in the data file!!!
This means that the file size is unchanged!
Deleted Packed
=========== ===========
|Header | |Header |
|-----------| |-----------|
|Valid 1 | |Valid 1 |
|-----------| |-----------|
|Deleted 1 | |Valid 2 |
|-----------| |-----------|
|Valid 2 | |Valid 3 |
|-----------| |===========|
|Deleted 2 | |EOF |
|-----------| |===========|
|Deleted 3 | |Deleted 1 |
|-----------| |-----------|
|Valid 3 | |Deleted 2 |
|===========| |-----------|
|EOF | |Deleted 3 |
=========== ===========
The data file can be truncated by using the COPY command.