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d4file(4)		   Kernel Interfaces Manual		     d4file(4)

NAME
       d4file -	D4-format binary file

SYNOPSIS
       d4file

DESCRIPTION
       The  universal  file  format for	storing	the list of 4-tuple data.  The
       file is called "D4-format file".	 D4-format file	consists of two	parts.
       A header	with 256byte data is put on the	head of	file; a	 magic	number
       for  recognizing	 file  format,	an attribute code, the number of data,
       lower- and higher-limit of data are held	in the header.	Data part fol-
       lows the	header;	list of	4-tuple	data, the quadruple of 2-byte-integers
       (short),	are put	in the data part.  Bit-	and byte-order	are  MSB-first
       (big-endian).  The file header is defined by the	following structure.

	      struct d4file {
		   char	   d4_magic[8];	    /* = "DATA0004" */
		   int32   d4_attrb;	    /* = 0 */
		   int32   d4_count;	    /* = 0 */
		   short   d4_llimit[4];    /* lower  limit of each member */
		   short   d4_hlimit[4];    /* higher limit of each member */
		   short   d4_spc[48];	    /* (filler)	*/
	      };

       d4_magic	field is always	filled with string "DATA0004".

       d4_attrb	holds the attribute code of file. The attribute	code is	always
       0.

       d4_count	 holds the number of 4-tuple data.  If this field is not used,
       constant	0 is set.

       d4_llimit and d4_hlimit arrays hold lower- and higher-limits of 4-tuple
       data respectively.

       d4_spc array is a dummy field, which is filled with zeros.

       Each 4-tuple data is defined by the following structure.

	      struct d4pac {
		   short   d4_data[4];
	      };

       The real	value held in  d4_data	can  be	 either	 signed	 2byte-integer
       (short)	and unsigned 2byte-integer (unsigned short).  The selection of
       the type	depends	on its application.

AUTHOR
       Copyright (C) 1995-1997 Hideaki Goto

       E-Mail: hgot@ecip.tohoku.ac.jp, hgot@aso.ecei.tohoku.ac.jp

				   July	1997			     d4file(4)

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