69
numbered from zero and not from one. Trace header for each trace record is summarized in
the Table below.
Offset
from trace
record
beginning
Parameter
length,
Bytes
Parameter
record
format
Comments
0
4
int
Trace sequence number within line
4
4
–
Unused
8
4
int
Original field record number
12
4
int
Trace sequence number within original field
record
16
4
–
Unused
20
4
int
CDP ensemble number
24
4
int
Trace sequence number within CDP
ensemble
28
2
short int
Trace identification code:
1 = seismic data;
2 = dead;
3 = dummy;
4 = time break;
5 = uphole;
6 = sweep;
7 = timing;
8 = water break;
9 = optional use.
30
2
short int
Number of vertically summed traces
yielding this trace
32
2
short int
Number of horizontally summed traces
yielding this trace
34
2
short int
Data use:
1 = production;
2 = test.
36
4
–
Unused
40
4
float
Altitude (mean-sea-level)
44
4
float
Height of geoid above WGS84 ellipsoid
48
4
int
Backward/toward direction (if negative -
backward)
52
4
float
Datum elevation at source in m (topography
offset)
56
14
–
Unused
70
2
short int
Scalar for coordinates:
+ = multiplier;
– = divisor.
