{
  "tracl": {"byte": 1, "type": "i","desc": "Trace sequence number within line"},
  "tracr": {"byte": 5, "type": "i","desc": "Trace sequence number within file"},
  "fldr": {"byte": 9, "type": "i","desc": "Original field record number"},
  "tracf": {"byte": 13, "type": "i","desc": "Trace number within original field record"},
  "ep": {"byte": 17, "type": "i","desc": "Energy source point number"},
  "cdp": {"byte": 21, "type": "i","desc": "Ensemble number"},
  "cdpt": {"byte": 25, "type": "i","desc": "Trace number within ensemble"},
  "trid": {"byte": 29, "type": "h","desc": "Trace identification code"},
  "nvs": {"byte": 31, "type": "h","desc": "Number of vertically summed traces"},
  "nhs": {"byte": 33, "type": "h","desc": "Number of horizontally summed traces"},
  "duse": {"byte": 35, "type": "h","desc": "Data use"},
  "offset": {"byte": 37, "type": "i","desc": "Distance from center of source point to center of receiver group"},
  "gelev": {"byte": 41, "type": "i","desc": "Receiver group elevation from sea level"},
  "selev": {"byte": 45, "type": "i","desc": "Surface elevation at source"},
  "sdepth": {"byte": 49, "type": "i","desc": "Source depth below surface"},
  "gdel": {"byte": 53, "type": "i","desc": "Datum elevation at receiver group"},
  "sdel": {"byte": 57, "type": "i","desc": "Datum elevation at source"},
  "swdep": {"byte": 61, "type": "i","desc": "Water depth at source"},
  "gwdep": {"byte": 65, "type": "i","desc": "Water depth at receiver group"},
  "scalel": {"byte": 69, "type": "h","desc": "Scalar to be applied to elevations and depths"},
  "scalco": {"byte": 71, "type": "h","desc": "Scalar to be applied to coordinates"},
  "sx": {"byte": 73, "type": "i","desc": "Source coodinate x"},
  "sy": {"byte": 77, "type": "i","desc": "Source coordinate y"},
  "gx": {"byte": 81, "type": "i","desc": "Group coordinate x"},
  "gy": {"byte": 85, "type": "i","desc": "Group coordinate y"},
  "counit": {"byte": 89, "type": "h","desc": "Coordinate units"},
  "wevel": {"byte": 91, "type": "h","desc": "Weathering velocity"},
  "swevel": {"byte": 93, "type": "h","desc": "Subewathering velocity"},
  "sut": {"byte": 95, "type": "h","desc": "Uphole time at source (ms)"},
  "gut": {"byte": 97, "type": "h","desc": "Uphole time at receiver group"},
  "sstat": {"byte": 99, "type": "h","desc": "Source static correction"},
  "gstat": {"byte": 101, "type": "h","desc": "Group static correction"},
  "tstat": {"byte": 103, "type": "h","desc": "Total static applied"},
  "laga": {"byte": 105, "type": "h","desc": "Lag time A"},
  "lagb": {"byte": 107, "type": "h","desc": "Lag time B"},
  "delrt": {"byte": 109, "type": "h","desc": "Delay recording time"},
  "muts": {"byte": 111, "type": "h","desc": "Mute time start"},
  "mute": {"byte": 113, "type": "h","desc": "Mute time end"},
  "ns": {"byte": 115, "type": "H","desc": "Number of samples"},
  "dt": {"byte": 117, "type": "H","desc": "Sample interval"},
  "gain": {"byte": 119, "type": "h","desc": "Gain type of field instrument code"},
  "igc": {"byte": 121, "type": "h","desc": "Instrument gain constant"},
  "igi": {"byte": 123, "type": "h","desc": "Instrument iniial gain"},
  "corr": {"byte": 125, "type": "h","desc": "Correlated"},
  "sfs": {"byte": 127, "type": "h","desc": "Sweep frequency start"},
  "sfe": {"byte": 129, "type": "h","desc": "Sweep frequency end"},
  "slen": {"byte": 131, "type": "h","desc": "Sweep length"},
  "styp": {"byte": 133, "type": "h","desc": "Sweep type code"},
  "stas": {"byte": 135, "type": "h","desc": "Sweep trace length at start"},
  "stae": {"byte": 137, "type": "h","desc": "Sweep trace length at end"},
  "tatyp": {"byte": 139, "type": "h","desc": "Taper type"},
  "afilf": {"byte": 141, "type": "h","desc": "Alias filter frequency"},
  "afils": {"byte": 143, "type": "h","desc": "Alias filter slope"},
  "nofilf": {"byte": 145, "type": "h","desc": "Notch filter frequency"},
  "nofils": {"byte": 147, "type": "h","desc": "Notch filter slope"},
  "lcf": {"byte": 149, "type": "h","desc": "Low-cut frequency"},
  "hcf": {"byte": 151, "type": "h","desc": "High-cut frequency"},
  "lcs": {"byte": 153, "type": "h","desc": "Low-cut slope"},
  "hcs": {"byte": 155, "type": "h","desc": "High-cut slope"},
  "year": {"byte": 157, "type": "h","desc": "Year data recorded"},
  "day": {"byte": 159, "type": "h","desc": "Day of year"},
  "hour": {"byte": 161, "type": "h","desc": "Hour of day"},
  "minute": {"byte": 163, "type": "h","desc": "Minute of hour"},
  "sec": {"byte": 165, "type": "h","desc": "Second of minute"},
  "timbas": {"byte": 167, "type": "h","desc": "Time basis code"},
  "trwf": {"byte": 169, "type": "h","desc": "Trace weighting factor"},
  "grnors": {"byte": 171, "type": "h","desc": "Geophone group number of roll switch"},
  "grnofr": {"byte": 173, "type": "h","desc": "Geophone group number of trace one within original field record"},
  "grnlof": {"byte": 175, "type": "h","desc": "Geophone group number of last trace within original field record"},
  "gaps": {"byte": 177, "type": "h","desc": "Gap size"},
  "otrav": {"byte": 179, "type": "h","desc": "Overtravel taper code"},
  "d1": {"byte": 181, "type": "f","desc": "Sample spacing for non-seismic data"},
  "f1": {"byte": 185, "type": "f","desc": "First sample location for non-seismic data"},
  "d2": {"byte": 189, "type": "f","desc": "Sample spacing between traces"},
  "f2": {"byte": 193, "type": "f","desc": "First trace location"},
  "ungpow": {"byte": 197, "type": "f","desc": "Negative of poser used for dynamic range compression"},
  "unscale": {"byte": 201, "type": "f","desc": "Reciprocal of scaling factor to normalize range"},
  "ntr": {"byte": 205, "type": "i","desc": "Number of traces"},
  "mark": {"byte": 209, "type": "h","desc": "Mark selected traces"},
  "shortpad": {"byte": 211, "type": "h","desc": "Alignment padding"},
  "cdpx": {"byte": 213, "type": "i","desc": "X-coordinate of ensemble"},
  "cdpy": {"byte": 217, "type": "i","desc": "Y-coordinate of ensemble"},
  "iline": {"byte": 221, "type": "i","desc": "Inline number"},
  "xline": {"byte": 225, "type": "i","desc": "Crossline number"},
  "sp": {"byte": 229, "type": "i","desc": "Shotpoint number"},
  "int64": {"byte": 233, "type": "q","desc": "Unused"}
}
