To write a tape in exactly the SEGY format as specified by the SEG's Digital Tape Standards book, you will need to supply the ASCII and binary tape reel header files which will become the EBCDIC and binary tape reel headers in the SEGY tape or file. These are the files ``header'' and ``binary'' created by segywrite.
If you don't have the ``binary'' and ``header'' files, then you must create them with the program segyhdrs (pronounced SEG Y headers) The command
% segyhdrs < data.suwill write the files ``header'' and ``binary'' in the current working directory. As an example, make some test data with suplane and then run segyhdrs on it
% suplane > data.su % segyhdrs < data.suYou will see the files binary and header appear in your current working directory.
The program has options that will allow you to set the values of binary header fields. These fields may be seen by typing:
% sukeyword jobid int jobid; /* job identification number */ int lino; /* line number (only one line per reel) */ int reno; /* reel number */ short ntrpr; /* number of data traces per record */ short nart; /* number of auxiliary traces per record */ unsigned short hdt; /* sample interval in micro secs for this reel */ unsigned short dto; /* same for original field recording */ ...where ``jobid'' is the first binary header field.
The file ``header'' is an ASCII file which may be edited with a normal text editor. You can put anything in there, as long as the format is 40 lines of 80 characters each. Segywrite will automatically convert this program The default header file created by segyhdrs looks like this
C This tape was made at the C C Center for Wave Phenomena C Colorado School of Mines C Golden, CO, 80401 C ... C C