Extracts SEISAN version from given data chunk.

data : string
Data chunk.
tuple, ([ ‘<’ | ‘>’ ], [ 32 | 64 ], [ 6 | 7 ])
Byte order (little endian ‘<’ or big endian ‘>’), architecture (32 or 64) and SEISAN version (6 or 7).

From the SEISAN documentation:

When Fortran writes a files opened with "form=unformatted", additional
data is added to the file to serve as record separators which have to
be taken into account if the file is read from a C-program or if read
binary from a Fortran program. Unfortunately, the number of and meaning
of these additional characters are compiler dependent. On Sun, Linux,
MaxOSX and PC from version 7.0 (using Digital Fortran), every write is
preceded and terminated with 4 additional bytes giving the number of
bytes in the write. On the PC, Seisan version 6.0 and earlier using
Microsoft Fortran, the first 2 bytes in the file are the ASCII
character "KP". Every write is preceded and terminated with one byte
giving the number of bytes in the write. If the write contains more
than 128 bytes, it is blocked in records of 128 bytes, each with the
start and end byte which in this case is the number 128. Each record is
thus 130 bytes long. All of these additional bytes are transparent to
the user if the file is read as an unformatted file. However, since the
structure is different on Sun, Linux, MacOSX and PC, a file written as
unformatted on Sun, Linux or MacOSX cannot be read as unformatted on PC
or vice versa.

The files are very easy to write and read on the same computer but
difficult to read if written on a different computer. To further
complicate matters, the byte order is different on Sun and PC. With 64
bit systems, 8 bytes is used to define number of bytes written. This
type of file can also be read with SEISAN, but so far only data written
on Linux have been tested for reading on all systems.

From version 7.0,the Linux and PC file structures are exactly the same.
On Sun the structure is the same except that the bytes are swapped.
This is used by SEISAN to find out where the file was written. Since
there is always 80 characters in the first write, character one in the
Linux and PC file will be the character P (which is represented by 80)
while on Sun character 4 is P.