Encana Segy 240 Trace header proposal (2D,3D)

Byte	Format	Key	Encana (Note Key 1=Must Have 2=Should Have)
1	I4		Trace sequential counter within line
5	I4		Trace sequential counter within volume
9	I4	1	3D LINE_SEQUENCE_NUMBER
13	I4	1	3D TRACE_SEQUENCE_NUMBER
17	R4	1	2D SHOT_SEQUENCE_NUMBER (interpolated station number)
21	I4	1	2D CDP_NUMBER
25	I4		Surface SHOT POINT (stack) or TRACE_SEQUENCE_NUMBER in ensemble (field)
29	I2		Trace identification code:
			1 = seismic
			2 = dead trace (zero amplitude)
31	I2		Number of vertically summed traces
33	I2		Number of horizontally stacked traces
35	I2		Data use 1=production 2=test
37	R4		SOURCE_RECEIVER_OFFSET
41	R4	2	surface elevation (water depth) above this CDP or receiver group elevation
45	R4		Surface elevation (water depth) at source
49	R4		source depth below surface ( a positive number)
53	R4	2	Floating Datum elevation at receiver (trace) group
57	R4		Floating Datum elevation at source
61	R4		Water depth at source
65	R4		Water depth at group
69	I2		Weathering velocity
71	I2		Subweathering velocity
73	R4		SOURCE_X_LOCATION
77	R4		SOURCE_Y_LOCATION
81	R4	1	Bin UTM X
85	R4	1	Bin UTM Y
89	R4		RECEIVER_X_LOCATION
93	R4		RECEIVER_Y_LOCATION
97	I2		Uphole time at group in milliseconds or gun cable static correction
99	I2	2	source static (0 if no SP)
101	I2		receiver static correction in milliseconds
103	I2	2	total static applied
105	I2		Bulk Time in ms between first sample on tape
			and zero time on the data
107	I2		lag time B. Time in ms between time break and the initiation time
			of the energy source. May be positive or negative.
109	I2		First break pick times or WB pick = Delay recording time
111	I2		mute time - start at near offset (ms)
113	I2		mute time - end at far offset (ms)
115	I2		Number of samples in this trace (should be less than or equal to the
			value stored in the File Identification Header at byte 3221 - 3222).
117	I2		Sample interval in microseconds (same as byte 3217 - 3218 in the
			File Identification Header).
119	I2		gain type of field instruments:
			1 = fixed
			2 = binary
			3 = floating point
			4 - N = optional use
121	I2		instrument gain constant
123	I2		instrument early or initial gain (dB)
125	I2		correlated: 1=no 2=yes
127	I2		sweep frequency start
129	I2		sweep frequency end
131	I2		sweep length in ms
133	I2		sweep type:
			1 = linear
			2 = parabolic
			3 = exponential
			4 = other
135	I2		sweep trace taper length at start in ms
137	I2		sweep trace taper length at end in ms
139	I2		taper type:
			1 = linear
			2 = cos2
			3 = other
141	I2		Alias filter frequency if used
143	I2		Alias filter slope
145	I2		Notch filter frequency if used
147	I2		Notch filter slope
149	I2		low cut frequency if used
151	I2		high cut frequency if used
153	I2		low cut frequency if used
155	I2		high cut slope
157	I2		Year data recorded
159	I2		Julian day of the year
161	R4		PEAK_VAL
165	R4		AVG_VAL
169	R4		RMS_VAL
173	I4		Receiver station number
			Record
177	I2		gap size
179	I2		Overtravel associated with taper at beginning of end of line:
			1 = down (or behind)
			2 = up (or ahead)
181	R4	2	Latitude Decimal Degrees
185	R4	2	Longitude Decimal Degrees
189	I4		Original field record number unique add 10k if duplicates
193	I4		Original field trace number (channel number)
197	R4		shot point surface station number (also CHEV_SP original Chevron shot point number)
201	I2		Uphole time at source in milliseconds
203	I2		Trace value measurement 1=pascal 2=volts
205	Special6		Transduction Constant see SEG Y rev1
211	I2		Transduction Units
213	I2		Device/Trace Identifier
215	I2		Hour of day recorded
217	I2		Source Type/Orientation
219	I2		Source Energy Direction
225	Special6		Source Measurement
231	I2		Source Measurement Unit
233	I2		Swath or sail line number
235	I2		Sequence number of sailed line
237	I2		Swath or sail line number / source line number
239	I2		Water Bottom pick times