NAME

     dds_disco - Disco format, Data Dictionary System


SYNOPSIS

     Data Dictionary System, Disco binary format.


DESCRIPTION

     DDS supports the Cogniseis Disco seismic format.

         format= disco  attributes

     No attributes are recognized by the  Disco  format.   Varia-
     tions  associated with the media (disk, tape, pipe) are han-
     dled automatically.

     The format is described by one major type, disco_trace.  The
     fields  created within the type are dependent upon the input
     format.  Global information is described by  a  pseudo  line
     header.  This format is created using the DDS_PATH/disco.fmt
     dictionary.  DDS_PATH/disco.map provides default map defini-
     tions.


LINE HEADER

     The Disco  line  is  summarized  by  twelve  values.   These
     values,  associated with the binary data, are also available
     as dictionary definitions (i.e. disco_SAMP_RATE= ...).  They
     may  be examined in the dictionary by end users or retrieved
     by application  programs.   End  users  may  override  these
     values, except for NUM_SAMP.

         comment= override binary header value
         disco_MAXNTR= 48
         disco_SAMP_RATE= 8000

     The definitions for the pseudo line header may be summarized
     by  their  name, type, and nominal element count.  Each name
     is prefixed by "disco_", when defined in a dictionary.

     tab(|);  l  l  l  lB  lB  lB  lB   l.    Name|Type|N|Comment
     SAMP_UNITS=|char|8|Sampling   units   ("MS",  "US",  "FEET",
     "METERS")          SAMP_RATE=|float|1|Sampling          rate
     NUM_SAMP=|int|1|Number      of      samples     in     trace
     SAMP_START=|float|1|Starting  coordinate  of  first   sample
     SAMP_DATUM=|char|16|Sample   datum,  origin  for  SAMP_START
     AMP_UNITS=|char|8|Amplitude   units   for   trace    samples
     DATA_CLASS=|char|16|Type   of  function  ("TX",  "FK",  ...)
     GEOMETRY=|char|16|Recording  geometry   ("SURFACE",   "VSP")
     ORDERNAM=|char|8|Primary   sort  order,  trace  header  name
     DIRECTION=|int|1|Sort   direction,   +1=ascend,   -1=descend
     MAXNTR=|int|1|Maximum   number   of   traces   per  ensemble
     NUM_FUNC=|int|1|Number of traces written to file


TRACE HEADER FIELDS

     The fields within the disco_trace type may be summarized  by
     their  name,  type,  and nominal element count.  Four fields
     are required, LASTTR, SEQNO, TYPE, and Samples.   The  Disco
     tape  format  requires  additional fields:  JobNum, UnitNum,
     ReelNum, ReelTrcNum,  LineTrcNum,  DatasetIndex,  x01010101,
     x02020202, x03030303, x04040404.

     tab(|);  l  l  l  lB  lB  lB  lB   l.    Name|Type|N|Comment
     TYPE|disco_int|1|"Trace    type,    0=normal,   1=auxiliary"
     SEQNO|disco_int|1|"Trace          sequence           number"
     LASTTR|disco_int|1|"Last  Trace  flag" Samples|disco_float|-
     1|"trace samples", last field.

     JobNum|disco_int|1|"Disco      tape,      seismic       job"
     UnitNum|disco_int|1|"Disco      tape,      logical     unit"
     ReelNum|disco_int|1|"Disco    tape,     relative     volume"
     ReelTrcNum|disco_int|1|"Disco      tape,     reel     trace"
     LineTrcNum|disco_int|1|"Disco     tape,     line      trace"
     DatasetIndex|disco_int|1|"Disco tape, dataset index"

     x01010101|disco_int|1|"Disco     tape,     magic      field"
     x02020202|disco_int|1|"Disco      tape,     magic     field"
     x03030303|disco_int|1|"Disco     tape,     magic      field"
     x04040404|disco_int|1|"Disco tape, magic field"


USP to DISCO FORMAT

     Special Disco fields are created, if the previous format was
     usp.   The fields within the disco_trace type may be summar-
     ized by their name, type, and nominal element count.

     tab(|);  l  l  l  lB  lB  lB  lB   l.    Name|Type|N|Comment
     FFID|disco_int|1|Field        Record       File       Number
     RCVRCO|disco_int|1|Receiver     component      xyz      code
     SHOTCO|disco_int|1|Source       component      xyz      code
     RECNUM|disco_int|1|record  number   CDP-STAT|disco_int|1|src
     point  above this depth pt SHOT|disco_int|1|permanent record
     number  PRI  CHAN|disco_int|1|permanent  trace  number   PTI
     SELEV|disco_float|1|source          point          elevation
     OFFSET|disco_int|1|unsigned     trace     distance      REC-
     STAT|disco_int|1|rec         location        index        GI
     SOFFSET|disco_int|1|signed          trace           distance
     RELEV|disco_float|1|group elevation CDPLBLS|disco_int|1|line
     index         3D         CDP|disco_int|1|depth         index
     CELEV|disco_float|1|depth           point          elevation
     STATIC|disco_int|1|static                         correction
     DSHIFT|disco_int|1|datum  shift  SHT-STAT|disco_int|1|source
     point number

     SHT-PREP|disco_float|1|PREP    Initiation    Static     SHT-
     UN|disco_float|1|Initiation     Static     Unapplied    SHT-
     SHFT|disco_float|1|Initiation    Static     Applied     REC-
     PREP|disco_float|1|PREP      Reception      Static      REC-
     UN|disco_float|1|Reception     Static     Unapplied     REC-
     SHFT|disco_float|1|Reception     Static     Applied     TOT-
     SHFT|disco_float|1|Total           Static            Applied
     TTIMAA|disco_float|1|Total   Timing   Adjust   Applied  TOT-
     UN|disco_float|1|Total           Static            Unapplied
     TTIMAU|disco_float|1|Total Timing Adjust Unapplied

     SHT-FDS|disco_int|1|Source  floating   datum   static   REC-
     FDS|disco_int|1|Receiver floating datum static

     SRAZMTH|disco_int|1|Source-to-Receiver     Azimuth      SHT-
     X|disco_float|1|Src     Point     X-Coordinate    3D    SHT-
     Y|disco_float|1|Src    Point    Y-Coordinate     3D     REC-
     X|disco_float|1|Rec     Point     X-Coordinate    3D    REC-
     Y|disco_float|1|Rec    Point    Y-Coordinate     3D     MID-
     X|disco_float|1|Src     Rec     Midpoint     X    3D    MID-
     Y|disco_float|1|Src    Rec    Midpoint     Y     3D     CDP-
     X|disco_float|1|CDP    Bin    Center   X   Coordinate   CDP-
     Y|disco_float|1|CDP     Bin     Center     Y      Coordinate
     CDPLAT|disco_int|1|depth      pt     lat     (deg*     10^5)
     CDPLON|disco_int|1|depth     pt     lon     (deg*      10^5)
     SHTLAT|disco_int|1|source     pt     lat     (deg*     10^5)
     SHTLON|disco_int|1|source pt lon (deg* 10^5)

     WDEPTH|disco_int|1|Water    Depth    Above    Depth    Point
     FOLD|disco_int|1|fold  RDATUM|disco_int|1|reference  surface
     elevation


USP to DISCO MAP

     Default map definition are provided for usp input.  Each map
     definition name is prefixed by "map:usp:disco.".

     tab(|);   lB   lB.    disco_field=|usp_expression    TYPE=|0
     SEQNO=|TrcNum LASTTR=|implicit

     FFID=|FlReFN  RCVRCO=|RcComp  SHOTCO=|SrComp  RECNUM=|RecNum
     CDP-STAT=|SrcPnt   SHOT=|PrRcNm  CHAN=|PrTrNm  SELEV=|SrPtEl
     OFFSET=|DstUsg       REC-STAT=|RecInd        SOFFSET=|DstSgn
     RELEV=|GrpElv   CDPLBLS=|LinInd   CDP=|DphInd  CELEV=|DePtEl
     STATIC=|StaCor DSHIFT=|DatShf SHT-STAT=|SoPtNm

     SHT-PREP=|PREPIn   SHT-UN=|InStUn   SHT-SHFT=|InStAp    REC-
     PREP=|PREPRc     REC-UN=|RcStUn     REC-SHFT=|RcStAp    TOT-
     SHFT=|ToStAp TTIMAA=|ToTmAA TOT-UN=|ToStUn TTIMAU=|ToTmAU

     SHT-FDS=|SrStat REC-FDS=|RcStat

     SRAZMTH=|SrRcAz  SHT-X=|SrPtXC  SHT-Y=|SrPtYC  REC-X=|RcPtXC
     REC-Y=|RcPtYC   MID-X=|SrRcMX   MID-Y=|SrRcMY  CDP-X=|CDPBCX
     CDP-Y=|CDPBCY CDPLAT=|DpPtLt  CDPLON=|DpPtLn  SHTLAT=|SrPtLt
     SHTLON=|SrPtLn
     WDEPTH=|WDepDP FOLD=|FoldNm RDATUM=|RfSrEl


SEGY to DISCO FORMAT

     Special Disco fields are created, if the previous format was
     segy.  The fields within the disco_trace type may be summar-
     ized by their name, type, and nominal  element  count.   For
     convenience,  the  comment  includes the byte numbers of the
     corresponding segy fields.

     tab(|);  l  l  l  lB  lB  lB  lB   l.    Name|Type|N|Comment
     LINETRC|disco_int|1|1:4,  Trace  sequence number within line
     REELTRC|disco_int|1|5:8, Trace sequence number  within  reel
     FFID|disco_int|1|9:12,    Original   field   record   number
     CHAN|disco_int|1|13:16, Trace  number  within  the  original
     field  rec  ESPNUM|disco_int|1|17:20,  Energy  source  point
     number CDP|disco_int|1|21:24, CDP ensemble number  |||25:28,
     Trace      number      within      the      CDP     ensemble
     TRACEID|disco_int|1|29:30, Trace  identification  code:  1-8
     VSTACK|disco_int|1|31:32, Number of vertically summed traces
     FOLD|disco_int|1|33:34,  Number  of   horizontally   stacked
     traces  DATAUSE|disco_int|1|35:36, Data use (1 production, 2
     test) SOFFSET|disco_int|1|37:40,  Distance  from  source  to
     group, signed RELEV|disco_int|1|41:44, Receiver group eleva-
     tion SELEV|disco_int|1|45:48, Surface  elevation  at  source
     SDEPTH|disco_int|1|49:52,  Source depth below surface (posi-
     tive) RDATUM|disco_int|1|53:56, Datum elevation at  receiver
     group  SDATUM|disco_int|1|57:60,  Datum  elevation at source
     WDEPTHSO|disco_int|1|61:64,   Water    depth    at    source
     WDEPTHRC|disco_int|1|65:68,   Water   depth   at  group  ED-
     SCAL|disco_int|1|69:70, Scalar to be applied to  all  eleva-
     tions CO-SCAL|disco_int|1|71:72, Scalar to be applied to all
     coordinates  SHT-X|disco_int|1|73:76,  Source  coordinate  X
     SHT-Y|disco_int|1|77:80,    Source    coordinate    Y   REC-
     X|disco_int|1|81:84,     Group     coordinate     X     REC-
     Y|disco_int|1|85:88,        Group        coordinate        Y
     COORUNIT|disco_int|1|89:90, Coordinate units  (1  length,  2
     arc   sec)   WVEL|disco_int|1|91:92,   Weathering   velocity
     SUBWVEL|disco_int|1|93:94,      Subweathering       velocity
     SHUPHOLE|disco_int|1|95:96,    Uphole    time    at   source
     RCUPHOLE|disco_int|1|97:98,    Uphole    time    at    group
     SHSTAT|disco_int|1|99:100,    Source    static    correction
     RCSTAT|disco_int|1|101:102,    Group    static    correction
     STAPPLY|disco_int|1|103:104,     Total     static    applied
     LAGTIMEA|disco_int|1|105:106,  Lag  time  A.  Time   in   ms
     LAGTIMEB|disco_int|1|107:108,   Lag   time  B.  Time  in  ms
     DELAY|disco_int|1|109:110, Delay recording time. Time in  ms
     MUTESTRT|disco_int|1|111:112,        Mute        time--start
     MUTEEND|disco_int|1|113:114,         Mute          time--end
     NSAMPLES|disco_int|1|115:116,  Number  of  samples  in  this
     trace SRATE|disco_int|1|117:118, Sample interval in  us  for
     this  trace GAINTYPE|disco_int|1|119:120, Gain type of field
     instruments:  1-4  INGCONST|disco_int|1|121:122,  Instrument
     gain constant INITGAIN|disco_int|1|123:124, Instrument early
     or initial gain (db) CORRFLAG|disco_int|1|125:126,  CorrFlag
     data  traces  (1  no,  2  yes) SWEEPSRT|disco_int|1|127:128,
     Sweep frequency at start SWEEPEND|disco_int|1|129:130, Sweep
     frequency  at end SWEEPLNG|disco_int|1|131:132, Sweep length
     in ms SWEEPTYP|disco_int|1|133:134, Sweep type (1 linear,  2
     par,  3 exp, 4 ?)  SWEEPSTP|disco_int|1|135:136, Sweep trace
     taper length at start  in  ms  SWEEPETP|disco_int|1|137:138,
     Sweep     trace     taper    length    at    end    in    ms
     TAPERTYP|disco_int|1|139:140, Taper type (1 linear, 2 cos^2,
     3  other)  ALIASFIL|disco_int|1|141:142,  Alias  filter fre-
     quency, if used ALIASLOP|disco_int|1|143:144,  Alias  filter
     slope  NOTCHFIL|disco_int|1|145:146, Notch filter frequency,
     if used  NOTCHSLP|disco_int|1|147:148,  Notch  filter  slope
     LOWCUT|disco_int|1|149:150,   Low  cut  frequency,  if  used
     HIGHCUT|disco_int|1|151:152, High  cut  frequency,  if  used
     LOWCSLOP|disco_int|1|153:154,       Low       cut      slope
     HICSLOP|disco_int|1|155:156,      High       cut       slope
     YEAR|disco_int|1|157:158,       Year      data      recorded
     DAY|disco_int|1|159:160,         Day         of         year
     HOUR|disco_int|1|161:162,   Hour  of  day  (24  hour  clock)
     MINUTE|disco_int|1|163:164,       Minute       of       hour
     SECOND|disco_int|1|165:166,       Second      of      minute
     TIMEBASE|disco_int|1|167:168, Time basis code  (1  local,  2
     gmt,  3 other) TRWEIGHT|disco_int|1|169:170, Trace weighting
     factor RSTASWP1|disco_int|1|171:172, Geophone  group  number
     of  roll switch pos 1 RSTATRC1|disco_int|1|173:174, Geophone
     group      number      of       trace       number       one
     RSTATRCN|disco_int|1|175:176,  Geophone group number of last
     trace GAPSIZE|disco_int|1|177:178, Gap size (total number of
     groups   dropped   OVERTRVL|disco_int|1|179:180,  Overtravel
     associated with taper

     |||181:240,  Unassigned--for   optional   information   CDP-
     STAT|disco_int|1|183:184,  src  point  above  this  depth pt
     SHT-STAT|disco_int|1|185:186,  source  point   number   REC-
     STAT|disco_int|1|187:188,     rec    location    index    GI
     SHOT|disco_int|1|189:190, shot number  RSTATSRC|disco_int|1|
     RSTATGRP|disco_int|1|


SEGY to DISCO MAP

     Default map definition are provided for  segy  input.   Each
     map definition name is prefixed by "map:segy:disco.".

     tab(|);   lB   lB.    disco_field=|segy_expression   TYPE=|0
     SEQNO=|CdpTrcNum LASTTR=|implicit

     LINETRC=|LineTrcNum  REELTRC=|ReelTrcNum   FFID=|FieldRecNum
     SHOT=|ShotNum CHAN=|FieldTrcNum ESPNUM=|SrcPtNum CDP=|CdpNum
     RECNUM=|field("RecNum",       void)       TRACEID=|TrcIdCode
     VSTACK=|VertStack      FOLD=|HorzStack      DATAUSE=|DataUse
     SOFFSET=|DstSgn        RELEV=|GrpElev         SELEV=|SrcElev
     SDEPTH=|SrcDepth      RDATUM=|GrpDatum      SDATUM=|SrcDatum
     WDEPTHSO=|WatDepthSrc       WDEPTHRC=|WatDepthGrp        ED-
     SCAL=|ElevScaler  CO-SCAL=|XYScaler  SHT-X=|SrcX SHT-Y=|SrcY
     REC-X=|GrpX  REC-Y=|GrpY  COORUNIT=|XYUnits   WVEL=|WeathVel
     SUBWVEL=|SubWeathVel                   SHUPHOLE=|UpholeTmSrc
     RCUPHOLE=|UpholeTmGrp  SHSTAT=|SrcStatic   RCSTAT=|GrpStatic
     STAPPLY=|TotalStatic LAGTIMEA=|LagTmBreak LAGTIMEB=|LagTmSrc
     DELAY=|LagTmSmpOne   MUTESTRT=|MuteStart    MUTEEND=|MuteEnd
     NSAMPLES=|TrcNumSmp    SRATE=|TrcSmpInt   GAINTYPE=|GainType
     INGCONST=|GainConst  INITGAIN=|GainInit   CORRFLAG=|CorrFlag
     SWEEPSRT=|SwpFreqStart                  SWEEPEND=|SwpFreqEnd
     SWEEPLNG=|SwpLength SWEEPTYP=|SwpType  SWEEPSTP=|SwpTprStart
     SWEEPETP=|SwpTprEnd                     TAPERTYP=|SwpTprType
     ALIASFIL=|AntiAliasFreq             ALIASLOP=|AntiAliasSlope
     NOTCHFIL=|NotchFreq  NOTCHSLP=|NotchSlope LOWCUT=|LowCutFreq
     HIGHCUT=|HighCutFreq                   LOWCSLOP=|LowCutSlope
     HICSLOP=|HighCutSlope       YEAR=|DateYear      DAY=|DateDay
     HOUR=|DateHour        MINUTE=|DateMin        SECOND=|DateSec
     TIMEBASE=|DateType  TRWEIGHT=|TrcWeight RSTASWP1=|RollSwtch1
     RSTATRC1=|RollTrace1                    RSTATRCN=|RollTraceN
     GAPSIZE=|RollGapSize  OVERTRVL=|OverTravel  CDP-STAT=|SrcPnt
     SHT-STAT=|SoPtNm REC-STAT=|RecInd


DEFAULT DISCO FORMAT

     A default Disco format is created, if the old format is  not
     usp or segy.  A Disco field is created for each input field.
     The new field name, type genus, size, and note  are  substi-
     tuted  from  the  input field.  The field is discard, if the
     input type is not integer, float,  or  complex.   The  field
     name is converted to upper case and truncated at eight char-
     acters.  Fields required by Disco are  automatically  added.
     An  error  is  issued, if the input fields contain any union
     types.


ADD, DROP

     The end user may explicitly add or drop fields in the  Disco
     format.

         comment= add two fields
         type:add_disco= {field_a field_b}
         fmt:*:disco.field_a= disco_int "field 'a' description"
         fmt:*:disco.field_b= disco_float "field 'b' description"

         comment= drop one field
         type:drop_disco= {field_x}


read_disco

     The read_disco definition allows the  end  user  to  request
     special  processing  when reading traces.  Keywords are used
     to request or reject individual  features.   Default  values
     are show in bold in the following table.

     tab(|); l l.  keyword|description, assuming  sort=  ?  SEQNO
     SHOT   RecNum|(deferred)  verify  sequential  sort_3  (SHOT)
     numbering   -RecNum|accept   any   sort_3    (SHOT)    value
     TrcNum|(deferred) verify sequential sort_2 (SEQNO) numbering
     -TrcNum|accept any sort_2 (SEQNO) value drop_dead|skip read,
     if  trace  is  dead  (NSAMPLES  <=  0) -drop_dead|allow dead
     traces to be read zero_dead|zero trace samples, if trace  is
     dead  -zero_dead|don't  change  samples,  if  trace  is dead
     pad_dead|(deferred) create dead traces,  if  sort_2  (SEQNO)
     not  sequential  -pad_dead|don't create dead traces, if non-
     sequential drop_live|skip read, if trace is live (TYPE == 0)
     -drop_live|allow  live traces to be read drop_aux|skip read,
     if trace is auxiliary (TYPE != 0) -drop_aux|allow  auxiliary
     traces to be read trc_sync|(deferred) reset trace counter to
     1, if sort_3 (SHOT) changes  -trc_sync|reset  trace  counter
     after  reaching  size_2 (NumTrc) trc_valid|(deferred) Error,
     if final sort_2 (SEQNO) is  not  sequential  -trc_valid|read
     anything you're given

     read_disco can be used to solve problems with  trace  input.
     The  following  examples  assume  there  are four traces per
     record.  Live traces are denoted by  (SEQNO,SHOT),  dead  by
     <SEQNO,SHOT>, and missing by "none".

        If "read_disco= " is defined (default), all input  traces
        are processed.

           tab(|); lB l l l l lB.   given|(1,5)|(2,5)|(3,5)|(4,5)
           |(1,9)|<2,9>|<3,9>|(4,9) |<1,9>|(2,9)|(3,9)|(4,9)|SHOT
           9 repeat |(1,n)|(2,n)|(3,n)|<4,n>

           read|(1,5)|(2,5)|(3,5)|(4,5)  |(1,9)|<2,9>|<3,9>|(4,9)
           |<1,9>|(2,9)|(3,9)|(4,9)|SHOT         9         repeat
           |(1,n)|(2,n)|(3,n)|<4,n>

        If  "read_disco=  drop_dead",  dead  input   traces   are
        dropped.

           tab(|); lB l l l l lB.   given|(1,5)|(2,5)|(3,5)|(4,5)
           |(1,9)|<2,9>|<3,9>|(4,9) |<1,9>|(2,9)|(3,9)|(4,9)|SHOT
           9 repeat |(1,n)|(2,n)|(3,n)|<4,n>

           read|(1,5)|(2,5)|(3,5)|(4,5)    |(1,9)|none|none|(4,9)
           |none|(2,9)|(3,9)|(4,9)|SHOT          9         repeat
           |(1,n)|(2,n)|(3,n)|none



write_disco

     The write_disco definition allows the end  user  to  request
     special  processing  when writing traces.  Keywords are used
     to request or reject individual  features.   Default  values
     are show in bold in the following table.
     tab(|); l l.  keyword|description, assuming  sort=  ?  SEQNO
     SHOT   RecNum|force   sequential   sort_3  (SHOT)  numbering
     -RecNum|honor sort_3 (SHOT) mapping TrcNum|force  sequential
     sort_2  (SEQNO)  numbering -TrcNum|honor sort_2 (SEQNO) map-
     ping  LASTTR|force  LASTTR  to  1,  when  next  SEQNO  ==  1
     -LASTTR|honor  LASTTR  mapping  NSAMPLES|force  NSAMPLES  to
     size_1  -NSAMPLES|honor  NSAMPLES   mapping   drop_dead|skip
     write,  if  trace  is  dead (NSAMPLES <= 0) -drop_dead|allow
     dead traces to be written zero_dead|zero trace  samples,  if
     trace  is  dead -zero_dead|don't change samples, if trace is
     dead pad_dead|create dead  traces,  if  sort_2  (SEQNO)  not
     sequential  -pad_dead|don't  create  dead  traces,  if  non-
     sequential drop_live|skip write, if trace is live  (TYPE  ==
     0)  -drop_live|allow live traces to be written drop_aux|skip
     write, if trace is auxiliary  (TYPE  !=  0)  -drop_aux|allow
     live traces to be written trc_sync|reset trace counter to 1,
     if sort_3 (SHOT) changes -trc_sync|reset trace counter after
     reaching  size_2  (NumTrc)  trc_valid|Error, if final sort_2
     (SEQNO) is not sequential -trc_valid|write  anything  you're
     given

     write_disco can be used to solve problems with trace  index-
     ing.   The  following  examples assume there are four traces
     per record.  Live traces are denoted by  (SEQNO,SHOT),  dead
     by <SEQNO,SHOT>, and missing by "none".

        If "write_disco= " is defined  (default),  output  traces
        are simply padded.  The header mapping for sort_2 (SEQNO)
        and sort_3 (SHOT) is preserved.

           tab(|); lB l l l l lB.   given|(1,5)|(2,5)|(3,5)|(4,5)
           |(1,9)|none|none|(4,9)  |none|(2,9)|(3,9)|(4,9)|SHOT 9
           repeat |(1,n)|(2,n)|(3,n)|none

           write|(1,5)|(2,5)|(3,5)|(4,5) |(1,9)|<2,9>|<3,9>|(4,9)
           |<1,9>|(2,9)|(3,9)|(4,9)|SHOT         9         repeat
           |(1,n)|(2,n)|(3,n)|<4,n>

        If "write_disco= TrcNum  RecNum", output is  sequentially
        numbered  and  padded.   The  header  mapping  for sort_2
        (SEQNO) and sort_3 (SHOT) is lost.

           tab(|); lB l l l l lB.   given|(?,?)|(?,?)|(?,?)|(?,?)
           |(?,?)|(?,?)|(?,?)|(?,?)     |(?,?)|(?,?)|none|none|10
           input traces

           write|(1,1)|(2,1)|(3,1)|(4,1) |(1,2)|(2,2)|(3,2)|(4,2)
           |(1,3)|(2,3)|<3,3>|<4,3>|pad last record

        If  "write_disco=  TrcNum",  output  sort_2  (SEQNO)   is
        sequential  and  padded.   The  header mapping for sort_3
        (SHOT) is preserved.
           tab(|);      lB      l      l      l       l       lB.
           given|(?,5)|(?,5)|(?,7)|(?,7)|SHOT       5       short
           |(?,7)|(?,7)|(?,8)|(?,8)|SHOT         7          wraps
           |(?,8)|none|none|none|SHOT 8 short and wraps

           write|(1,5)|(2,5)|(3,7)|(4,7)|SHOT       5       short
           |(1,7)|(2,7)|(3,8)|(4,8)|SHOT          7         wraps
           |(1,8)|<2,8>|<3,8>|<4,8>|SHOT 8 short and wraps

        If "write_disco= trc_sync TrcNum", output sort_2  (SEQNO)
        is  sequential,  padded  and synchronized with changes in
        sort_3 (SHOT).  The header mapping for sort_3  (SHOT)  is
        preserved.

           tab(|);      lB      l      l      l       l       lB.
           given|(?,5)|(?,5)|none|none|SHOT        5        short
           |(?,7)|(?,7)|(?,7)|(?,7) |(?,7)|(?,7)|none|none|SHOT 7
           repeat |(?,8)|(?,8)|none|none|SHOT 8 short

           write|(1,5)|(2,5)|<3,5>|<4,5> |(1,7)|(2,7)|(3,7)|(4,7)
           |(1,7)|(2,7)|<3,7>|<4,7> |(1,8)|(2,8)|<3,8>|<4,8>

        If "write_disco= trc_sync", output is padded  and  sort_2
        (SEQNO)  is  synchronized  with changes in sort_3 (SHOT).
        The header mapping for sort_2 (SEQNO) and  sort_3  (SHOT)
        is preserved.  This variation is particularly useful when
        converting to usp format, from a  format  which  may  not
        carry along dead traces (segy, disco).

           tab(|); lB l l l  l  lB.   given|(1,5)|none|(3,5)|none
           |none|(2,7)|none|(4,7) |(1,7)|(2,7)|(3,7)|(4,7)|SHOT 7
           repeat |(1,8)|none|none|(4,8)

           write|(1,5)|<2,5>|(3,5)|<4,5> |<1,7>|(2,7)|<3,7>|(4,7)
           |(1,7)|(2,7)|(3,7)|(4,7)|SHOT         7         repeat
           |(1,8)|<2,8>|<3,8>|(4,8)


SEE ALSO

     tab(|);  lB  l.   dds(1)|overview   dds_user(1)|user   guide
     dds_map(1)|map   expressions   dds_expert(1)|symbolic  names
     dds_format(1)|generic   format   dds_disco(1)|Disco   format
     dds_usp(1)|Disco     format     dds_segy(1)|Disco     format
     dds_rosetta(1)|Rosetta Stone, "Standard" formats

     cdds_api(3)|"C"      Application      Program      Interface
     fdds_api(3f)|Fortran Application Program Interface


AUTHOR

     R. L. Selzler, APR, Tulsa


COPYRIGHT

     copyright 2001, Amoco Production Company
               All Rights Reserved
          an affiliate of BP America Inc.



















































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