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 Map a short at location 229 to gain constant igc:			

	segyread <data >outdata remap=igc byte=229s			



 Or all combined: 							

	segyread <data >outdata remap=d1,sx,igc byte=221f,225l,229s	



 Segy header words are accessed as Xt where X denotes the byte number	

 starting at 1 in correspondance with the SEGY standard (1975)		

 Known types include:	f	float (4 bytes)				

 			l	long int (4 bytes)			

 			s	short int (2 bytes)			

 			b	byte (1 bytes)				



	  type:	  sudoc segyread   for further information		







 Note:

      If you have a tape with multiple sequences of ebcdic header,

	binary header,traces, use the device that

	invokes the no-rewind option and issue multiple segyread

	commands (making an appropriate shell script if you

	want to save all the headers).	Consider using >> if

	you want a single trace file in the end.  Similar

	considerations apply for multiple reels of tapes,

	but use the standard rewind on end of file.



 Note: For buff=1 (default) tape is accessed with 'read', for buff=0

	tape is accessed with fread. We suggest that you try buff=1

	even with EXABYTE tapes.

 Caveat: may be slow on an 8mm streaming (EXABYTE) tapedrive

 Warning: segyread or segywrite to 8mm tape is fragile. Allow sufficient

	time between successive reads and writes.

 Warning: may return the error message "efclose: fclose failed"

	intermittently when segyreading/segywriting to 8mm (EXABYTE) tape

	even if actual segyread/segywrite is successful. However, this

	error message may be returned if your tape drive has a fixed

	block size set.

 Caution: When reading or writing SEG-Y tapes, the tape

	drive should be set to be able to read variable block length

	tape files.





 Credits:

	SEP: Einar Kjartansson

	CWP: Jack K. Cohen, Brian Sumner, Chris Liner

	   : John Stockwell (added 8mm tape stuff)

 conv parameter added by:

	Tony Kocurko

	Department of Earth Sciences

	Memorial University of Newfoundland

	St. John's, Newfoundland

 read from stdin via tape=-  added by	Tony Kocurko

 bhed format = 2,3 conversion by:

	Remco Romijn (Applied Geophysics, TU Delft)

	J.W. de Bruijn (Applied Geophysics, TU Delft)

 bhed format = 8 conversion by: John Stockwell

 header remap feature added by:

 	Matthias Imhof, Virginia Tech

--------------------------

 Additional Notes: