Valid dBASE for Windows table file, bits 0-2 indicate version number: 3 for dBASE Level 5, 4 for dBASE Level 7.
Bit 3 and bit 7 indicate presence of a dBASE IV or dBASE for Windows memo file;
bits 4-6 indicate the presence of a dBASE IV SQL table; 
bit 7 indicates the presence of any .DBT memo file (either a dBASE III PLUS type or a dBASE IV or dBASE for Windows memo file). 


The first byte of the DBF file determines the xbase file version

76543210
00000000

|        -  True if any memo file
    |    -  True if Version 4 memo file
      || -  True for both V3 and V4 files




00000011  - Could be a version III or version IV file, lib defaults to IV
10000011  - Version III with memo
10001011  - Version IV with memo



Logic for checking for which version

  3      bit 4 not set, bit 5&6 set, if bit 0 set and bit 3 not set, then V3
  4      bit 4 not set, bit 5&6 set, if bit 0 set and bit 3 set
  5      bit 4 not set, bit 5&6 set, if bit 0 set and bit 3 set 
>=7      bit 4 set



		bit 0		bit 3				bit 4	bit 5	bit 6
V III	Optional	0					0		1		1			No field type F
V IV	Optional	if bit0 then 1		0		1		1			Supports field type F
V V		Optional	if bit0 then 1		0		1		1			Supports field type F

V VII	?			?					1		0		0



pseudocode logic

if not bit 4, and bit 5 and bit 6
{
	if V4 compiled in, if not (bit0 and not bit3)  return V4
	else
	if V3 compiled in and not bit3, and not prod mdx, return V3
}