SUKEYWORD - See SU Keywords

The next 5 programs that are discussed in this section have the option ``key='' in their selfdocs and the reference to the trace header field ``keywords.'' As has been discussed in Chapter 2, sukeyword is used to determine just what these header keywords are. Typing:

% sukeyword -o

shows this list. (You may also see this list in Appendix B.) However, of the 80+ fields which are defined in the SU header, only a relatively small subset are used most of the time. These fields are given by the sukeyword listing as

	int tracl;	/* trace sequence number within line */
	int tracr;	/* trace sequence number within reel */
	int cdp;	/* CDP ensemble number */
	int cdpt;	/* trace number within CDP ensemble */
 ...
	short trid;	/* trace identification code:
 ...			1 = seismic data

	int offset;	/* distance from source point to receiver
 ...
	int  sx;	/* X source coordinate */
	int  sy;	/* Y source coordinate */
	int  gx;	/* X group coordinate */
	int  gy;	/* Y group coordinate */
	short counit;	/* coordinate units code:
 ...
	short delrt;	/* delay recording time, time in ms between
			   initiation time of energy source and time
			   when recording of data samples begins
			   (for deep water work if recording does not
			   start at zero time) */
	unsigned short ns;	/* number of samples in this trace */
	unsigned short dt;	/* sample interval; in micro-seconds */

 ...
	/* local assignments */
	float d1;	/* sample spacing for non-seismic data */

	float f1;	/* first sample location for non-seismic data */

	float d2;	/* sample spacing between traces */

	float f2;	/* first trace location */

It is a good idea to be aware of this collection when using data derived either from modeling programs or from field datasets.