Provided by: gmt_6.4.0+dfsg-2build1_amd64 bug

NAME

       gmt - The Generic Mapping Tools data processing and display software package

INTRODUCTION

       GMT  is a collection of freely available command-line tools under the GNU LGPL that allows
       you to manipulate x,y and x,y,z data sets (filtering, trend fitting, gridding, projecting,
       etc.)  and  produce  illustrations  ranging  from  simple  x-y plots, via contour maps, to
       artificially illuminated surfaces and 3-D perspective views in black/white or full  color.
       Linear,  log10,  and  power  scaling  is  supported  in  addition  to  over  30 common map
       projections. The processing and display routines within GMT  are  completely  general  and
       will handle any (x,y) or (x,y,z) data as input.

SYNOPSIS

       gmt is the main program that can start any of the modules:

       gmt module module-options
              Starts  a  given GMT module with the module-options that pertain to that particular
              module.  A few special commands are also available:

       gmt clear items
              Deletes current defaults, or the  cache,  data  or  sessions  directories.   Choose
              between  defaults  (deletes  the  current gmt.conf file used for the current modern
              session), cache (deletes the user’s cache directory and all of its  content),  data
              (deletes  the  user’s data download directory and all of its content), or all (does
              all of the above).

       gmt begin [session-prefix] [format] [options]
              Initializes a new GMT session under modern mode [Default  is  classic  mode].   All
              work  is  performed  in  a  temporary  work directory.  The optional session-prefix
              assigns a  name  to  the  session,  and  this  may  be  used  as  figure  name  for
              single-figure  sessions [gmtsession].  Likewise, the optional format can be used to
              override the default graphics format [PDF].

       gmt figure prefix [format(s)] [options]
              Specifies the desired name, output format(s) and any custom arguments  that  should
              be passed to psconvert when producing this figure.  All subsequent plotting will be
              directed to this current figure until another gmt figure command is issued  or  the
              session  ends.   The prefix is used to build final figure names when extensions are
              automatically appended. The format setting is a  comma-separated  list  of  desired
              extensions (e.g., pdf,png).

       gmt inset [arguments]
              Allows  users  to  place  a  map inset by temporarily changing where plotting takes
              place as well as the region and projection, then resets to previous stage.

       gmt subplot [arguments]
              Allows users to create a matrix of panels with automatic labeling and advancement.

       gmt end [show]
              Terminates a GMT modern mode session  and  automatically  converts  the  registered
              illustration(s)  to  their  specified  formats,  then eliminates the temporary work
              directory.  The figures are placed in the current directory.

       For information on any module, load the module documentation in your browser via gmt docs,
       e.g.:

          gmt docs grdimage

       If no module is given then several other options are available:

       --help List and description of GMT modules.

       --new-script[=L]
              Write  a  GMT modern mode script template to standard output. Optionally append the
              desired scripting language among bash, csh, or batch.  Default is  the  main  shell
              closest to your current shell (e.g., bash for zsh, csh for tcsh).

       --new-glue=name
              Write  the  C  code  glue  needed  when  building third-party supplements as shared
              libraries.  The name is the name of the shared library. Run gmt in the directory of
              the  supplement  and  the  glue code will be written to standard output.  Including
              this C code when building the shared library means gmt can list  available  modules
              via   the  --show-modules,  --help  options.   We  recommend  saving  the  code  to
              gmt_name_glue.c.

       --show-bindir
              Show directory of executables and exit.

       --show-citation
              Show the citation for the latest GMT publication.

       --show-classic
              List classic module names on standard output and exit.

       --show-classic-core
              List classic module names (core only) on standard output and exit.

       --show-cores
              Show number of available cores.

       --show-datadir
              Show data directory/ies and exit.

       --show-dataserver
              Show URL of the remote GMT data server.

       --show-dcw
              Show the DCW data version used.

       --show-doi
              Show the DOI of the current release.

       --show-gshhg
              Show the GSHHG data version used.

       --show-modules
              List modern module names on standard output and exit.

       --show-modules-core
              List modern module names (core only) on standard output and exit.

       --show-library
              Show the path of the shared GMT library.

       --show-plugindir
              Show plugin directory and exit.

       --show-sharedir
              Show share directory and exit.

       --show-userdir
              Show full path of user’s ~/.gmt dir and exit.

       --version
              Print version and exit.

       =      Check if that module exist and if so the  program  will  exit  with  status  of  0;
              otherwise the status of exit will be non-zero.

COMMAND-LINE COMPLETION

       GMT  provides  basic  command-line  completion  (tab completion) for bash.  The completion
       rules      are      either      installed      in      /etc/bash_completion.d/gmt       or
       <prefix>/share/tools/gmt_completion.bash.   Depending  on  the distribution, you may still
       need to source the gmt completion file from ~/.bash_completion  or  ~/.bashrc.   For  more
       information see Section Command-line completion in the CookBook.

GMT MODULES

       Run  gmt  --help to print the list of all core and supplementals modules within GMT, and a
       very short description of their purpose.  Detailed information about each program  can  be
       found in the separate manual pages.

CUSTOM MODULES

       The  gmt  program can also load custom modules from shared libraries built as specified in
       the GMT API documentation.  This way your modules can benefit from the GMT  infrastructure
       and extend GMT in specific ways.

THE COMMON GMT OPTIONS

       -B[p|s]parameters                       -Jparameters                       -Jz|Zparameters
       -Rwest/east/south/north[/zmin/zmax][+r][+uunit]  -U[stamp]  -V[level]  -X[a|c|f|r][xshift]
       -Y[a|c|f|r][yshift]  -aflags -bbinary -crow,col|index -dnodata[+ccol] -eregexp -fflags -g‐
       gaps -hheaders -iflags -jflags -lflags -nflags -oflags -pflags -qflags -rreg  -sflags  -t‐
       transp -x[[-]n] -:[i|o]

DESCRIPTION

       These  are  all  the common GMT options that remain the same for all GMT modules. No space
       between the option flag and the associated arguments.

   The -B option
       Syntax

       -B[p|s]parameters
              Set map boundary frame and axes attributes. (See cookbook information).

       Description

       This is potentially the most complicated option in GMT, but most examples of its usage are
       actually  quite simple. We distinguish between two sets of information: Frame settings and
       Axes settings.  These are set separately by their own -B invocations;  hence  multiple  -B
       specifications may be specified. The Frame settings cover things such as which axes should
       be plotted, canvas fill, plot title (and subtitle), and what type of gridlines  be  drawn,
       whereas the Axes settings deal with annotation, tick, and gridline intervals, axes labels,
       and annotation units.

   Frame settings
       The Frame settings are specified by
          -B[axes][+b][+gfill][+i[val]][+n][+olon/lat][+ssubtitle][+ttitle][+w[pen]][+xfill][+yfill][+zfill]

       The  frame  setting  is  optional  but  can  be invoked once to override the defaults. The
       following modifiers can be appended to -B to control the Frame settings:

       • axes to set which of the axes should be drawn and possibly annotated using a combination
         of  the codes listed below [default is theme dependent]. Borders omitted from the set of
         codes will not be drawn.  For  example,  WSn  denotes  that  the  “western”  (left)  and
         “southern”  (bottom) axes should be drawn with tick-marks and annotations by using W and
         S; that the “northern” (top) edge of the  plot  should  be  drawn  with  tick-marks  and
         without  annotations by using n; and that the “eastern” (right) axes should not be drawn
         by not including one of E|e|r.

            • West, East, South, North, and/or (for 3-D plots) Z indicate  axes  that  should  be
              drawn with both tick-marks and annotations.

            • west,  east,  south,  north,  and/or (for 3-D plots) z indicate axes that should be
              drawn with tick-marks but without annotations.

            • l(eft), r(ight), b(ottom), t(op) and/or (for 3-D plots)  u(p)  indicate  axes  that
              should be drawn without tick-marks or annotations.

       • Z|zcode  (for 3-D plots) where code is any combination of the corner ids 1, 2, 3, 4.  By
         default, a single vertical axes will be plotted for 3-D plots at the most  suitable  map
         corner.  code  can  be  used  to  override  this,  where  1 represents the south-western
         (lower-left)  corner,  2  the   south-eastern   (lower-right),   3   the   north-eastern
         (upper-right), and 4 the north-western (upper-left) corner.

       • +w[pen]  (for  3-D  plots) to draw the outlines of the x-z and y-z planes [default is no
         outlines]. Optionally, append pen  to  specify  different  pen  attributes  [default  is
         MAP_GRID_PEN_PRIMARY].

       • +b (for 3-D plots) to draw the foreground lines of the 3-D cube defined by -R.

       • +gfill to paint the interior of the canvas with a color specified by fill [default is no
         fill]. This also sets fill for the two back-walls in 3-D plots.

       • +xfill to paint the yz plane with a color specified by fill [default is no fill].

       • +yfill to paint the xz plane with a color specified by fill [default is no fill].

       • +zfill to paint the xy plane with a color specified by fill [default is no fill].

       • +i[val] to annotate an internal meridian or parallel when the axis that  normally  would
         be  drawn and annotated does not exist (e.g., for an azimuthal map with 360-degree range
         that has no latitude axis or a global Hammer map that has no longitude axis). val  gives
         the meridian or parallel that should be annotated [default is 0].

       • +olon/lat  to produce oblique gridlines about another pole specified by lon/lat [default
         references to the North pole]. +o is ignored if no gridlines are requested.

       • +n to have no frame and annotations at all [default is contolled by axes].

       • +ttitle to place the string given in title centered above the plot frame [default is  no
         title].

       • +ssubtitle  (requires  +ttitle)  to place the string given in subtitle beneath the title
         [default is no subtitle].

       Note: Both +ttitle and +ssubtitle may be set over multiple lines by breaking them up using
       the  markers  @^  or  <break>.   To  include  LaTeX code as part of a single-line title or
       subtitle, enclose the expression with @[  markers  (or  alternatively  <math>  …  </math>)
       (requires latex and dvips to be installed). See the Using LaTeX Expressions in GMT chapter
       for more details.

   Axes settings
       The Axes settings are specified by
          -B[p|s][x|y|z]intervals[+aangle|n|p][+f][+llabel][+pprefix][+uunit]

       but you may also split this into two separate invocations for clarity, i.e.,
          -B[p|s][x|y|z][+aangle|n|p][+e[l|u]][+f][+l|Llabel][+pprefix][+s|Sseclabel][+uunit]
          -B[p|s][x|y|z]intervals

       The following modifiers can be appended to -B to control the Axes settings:

       • p|s to set whether the modifiers apply to the p(rimary) or s(econdary) axes [Default  is
         p].   These  settings  are  mostly  used for time axes annotations but are available for
         geographic axes as well. Note: Primary refers to annotations closest  to  the  axis  and
         secondary   to  annotations  further  away.   Hence,  primary  annotation-,  tick-,  and
         gridline-intervals  must  be  shorter  than  their  secondary  counterparts.  The  terms
         “primary”  and “secondary” do not reflect any hierarchical order of units: the “primary”
         annotation interval is usually smaller (e.g., days)  while  the  “secondary”  annotation
         interval typically is larger (e.g., months).

       • x|y|z  to  set  which  axes  the modifiers apply to [default is xy]. If you wish to give
         different annotation intervals or labels for the various axes then you must repeat the B
         option  for  each axis. For a 3-D plot with the -p and -Jz options used, -Bz can be used
         to provide settings for the vertical axis.

       • +e to give skip annotations that fall exactly at the ends of the axis.  Append l or u to
         only skip the lower or upper annotation, respectively.

       • +f  (for  geographic axes only) to give fancy annotations with W|E|S|N suffices encoding
         the sign.

       • +l|+Llabel (for Cartesian plots only) to add a label to an axis.  +l  uses  the  default
         label  orientation;  +L  forces  a horizontal label for y-axes, which is useful for very
         short labels.

       • +s|Sseclabel (for Cartesion plots only) to specify an alternate label for the  right  or
         upper  axes.   +s  uses  the default label orientation; +S forces a horizontal label for
         y-axes, which is useful for very short labels.

       • +pprefix (for Cartesion plots only) to  define  a  leading  text  prefix  for  the  axis
         annotation  (e.g.,  dollar  sign  for  plots  related to money). For geographic maps the
         addition of degree symbols, etc. is automatic and controlled by FORMAT_GEO_MAP.

       • +uunit (for Cartesion plots only) to append  specific  units  to  the  annotations.  For
         geographic  maps  the  addition  of  degree symbols, etc. is automatic and controlled by
         FORMAT_GEO_MAP.

       • +aangle (for Cartesion plots only) to plot slanted annotations, where angle is  measured
         with  respect  to the horizontal and must be in the -90 <= angle <= 90 range. +an can be
         used as a shorthand for normal (i.e., +a90) [Default for y-axis] and  +ap  for  parallel
         (i.e.,  +a0)  annotations  [Default  for  x-axis].  These  defaults  can  be changed via
         MAP_ANNOT_ORTHO.

       • intervals to define the intervals for annotations and major  tick  spacing,  minor  tick
         spacing,  and/or  grid  line  spacing.  See  Intervals  Specification for the formatting
         associated with this modifier.

       NOTE: To include LaTeX code as part of a label, enclose the expression with @[ markers (or
       alternatively <math> … </math>). (requires latex and dvips to be installed). See the Using
       LaTeX Expressions in GMT chapter for more details.

       NOTE: If any labels, prefixes, or units contain spaces or special characters you will need
       to enclose them in quotes.

       NOTE:  Text items such as title, subtitle, label and seclabel are seen by GMT as part of a
       long string containing everything passed to -B. Therefore, they cannot contain  substrings
       that  look  like  other  modifiers.  If you need to embed such sequences (e.g., +t“Solving
       a+b=c”) you need to replace those + symbols  with  their  octal  equivalent  \053,  (e.g.,
       +t“Solving a\053b=c”).

       NOTE:  For  non-geographical  projections: Give negative scale (in -Jx) or axis length (in
       -JX) to change the direction of increasing coordinates (i.e., to make the y-axis  positive
       down).
       Intervals specification
       The intervals specification is a concatenated string made up of substrings of the form

          [a|f|g][stride][phase][unit].

       The  choice  of  a|f|g  sets  the  axis  item of interest, which are detailed in the Table
       interval types. Optionally, append phase to shift the annotations by that amount (positive
       or negative with the sign being required). Optionally, append unit to specify the units of
       stride, where unit is one of the 18 supported  unit  codes.  For  custom  annotations  and
       intervals,  intervals  can  be  given  as  cintfile,  where intfile contains any number of
       records with coord type [label]. See the section Custom axes for more details.

                               ┌─────┬──────────────────────────────────┐
                               │FlagDescription                      │
                               ├─────┼──────────────────────────────────┤
                               │a    │ Annotation   and   major    tick │
                               │     │ spacing                          │
                               ├─────┼──────────────────────────────────┤
                               │f    │ Minor tick spacing               │
                               ├─────┼──────────────────────────────────┤
                               │g    │ Grid line spacing                │
                               └─────┴──────────────────────────────────┘

       NOTE:  The  appearance  of  certain time annotations (month-, week-, and day-names) may be
       affected  by  the  GMT_LANGUAGE,  FORMAT_TIME_PRIMARY_MAP,  and  FORMAT_TIME_SECONDARY_MAP
       settings.

       Automatic  intervals:  GMT  will auto-select the spacing between the annotations and major
       ticks, minor ticks, and grid lines if stride is not provided  after  a|f|g.  This  can  be
       useful  for  automated  plots  where  the  region  may  not  always be the same, making it
       difficult to determine the appropriate stride in advance. For example, -Bafg  will  select
       all  three spacings automatically for both axes. In case of longitude–latitude plots, this
       will keep the spacing the same on both axes. You can also use -Bxafg -Byafg to auto-select
       them  separately. Note that given the myriad ways of specifying time-axis annotations, the
       automatic selections may need to be overridden with manual  settings  to  achieve  exactly
       what  you  need.  When stride is omitted after g, the grid line are spaced the same as the
       minor ticks; unless g is used in consort with a, in which case the grid lines  are  spaced
       the same as the annotations.

       Stride  units:  The unit flag can take on one of 18 codes which are listed in Table Units.
       Almost all of these units are time-axis specific. However, the d, m, and s units  will  be
       interpreted as arc degrees, minutes, and arc seconds respectively when a map projection is
       in effect.

                           ┌─────┬────────────────┬──────────────────────────┐
                           │FlagUnitDescription              │
                           ├─────┼────────────────┼──────────────────────────┤
                           │Y    │ year           │ Plot using all 4 digits  │
                           ├─────┼────────────────┼──────────────────────────┤
                           │y    │ year           │ Plot using last 2 digits │
                           ├─────┼────────────────┼──────────────────────────┤
                           │O    │ month          │ Format annotation  using │
                           │     │                │ FORMAT_DATE_MAP          │
                           ├─────┼────────────────┼──────────────────────────┤
                           │o    │ month          │ Plot  as 2-digit integer │
                           │     │                │ (1–12)                   │
                           ├─────┼────────────────┼──────────────────────────┤
                           │U    │ ISO week       │ Format annotation  using │
                           │     │                │ FORMAT_DATE_MAP          │
                           ├─────┼────────────────┼──────────────────────────┤
                           │u    │ ISO week       │ Plot  as 2-digit integer │
                           │     │                │ (1–53)                   │
                           ├─────┼────────────────┼──────────────────────────┤
                           │r    │ Gregorian week │ 7-day stride from  start │
                           │     │                │ of       week       (see │
                           │     │                │ TIME_WEEK_START)         │
                           ├─────┼────────────────┼──────────────────────────┤
                           │K    │ ISO weekday    │ Plot name of weekday  in │
                           │     │                │ selected language        │
                           ├─────┼────────────────┼──────────────────────────┤
                           │k    │ weekday        │ Plot  number  of  day in │
                           │     │                │ the  week   (1–7)   (see │
                           │     │                │ TIME_WEEK_START)         │
                           ├─────┼────────────────┼──────────────────────────┤
                           │D    │ date           │ Format  annotation using │
                           │     │                │ FORMAT_DATE_MAP          │
                           └─────┴────────────────┴──────────────────────────┘

                           │d    │ day            │ Plot day of month (1–31) │
                           │     │                │ or  day  of year (1–366) │
                           │     │                │ (see FORMAT_DATE_MAP)    │
                           ├─────┼────────────────┼──────────────────────────┤
                           │R    │ day            │ Same as  d;  annotations │
                           │     │                │ aligned  with  week (see │
                           │     │                │ TIME_WEEK_START)         │
                           ├─────┼────────────────┼──────────────────────────┤
                           │H    │ hour           │ Format annotation  using │
                           │     │                │ FORMAT_CLOCK_MAP         │
                           ├─────┼────────────────┼──────────────────────────┤
                           │h    │ hour           │ Plot  as 2-digit integer │
                           │     │                │ (0–24)                   │
                           ├─────┼────────────────┼──────────────────────────┤
                           │M    │ minute         │ Format annotation  using │
                           │     │                │ FORMAT_CLOCK_MAP         │
                           ├─────┼────────────────┼──────────────────────────┤
                           │m    │ minute         │ Plot  as 2-digit integer │
                           │     │                │ (0–60)                   │
                           ├─────┼────────────────┼──────────────────────────┤
                           │S    │ seconds        │ Format annotation  using │
                           │     │                │ FORMAT_CLOCK_MAP         │
                           ├─────┼────────────────┼──────────────────────────┤
                           │s    │ seconds        │ Plot  as 2-digit integer │
                           │     │                │ (0–60)                   │
                           └─────┴────────────────┴──────────────────────────┘

       NOTE: If your axis is in radians you can use multiples or fractions  of  pi  to  set  such
       annotation intervals. The format is [s]pi[f], for an optional integer scale s and optional
       integer fraction f. When GMT parses one of these forms we alert the labeling machinery  to
       look  for  certain  combinations  of  pi, limited to npi, 3/2 pi (3pi2), and fractions 3/4
       (3pi4), 2/3 (2pi3), 1/2 (1pi2), 1/3 (1pi3), and 1/4 (1pi4) in the interval given to the -B
       axes  settings.  When an annotated value is within roundoff-error of these combinations we
       typeset the label using the Greek letter \pi and required multiples or fractions.

       NOTE: These GMT parameters can affect the appearance of the map boundary:
              MAP_ANNOT_MIN_ANGLE,           MAP_ANNOT_MIN_SPACING,           FONT_ANNOT_PRIMARY,
              FONT_ANNOT_SECONDARY,     MAP_ANNOT_OFFSET_PRIMARY,     MAP_ANNOT_OFFSET_SECONDARY,
              MAP_ANNOT_ORTHO, MAP_FRAME_AXES, MAP_DEFAULT_PEN,  MAP_FRAME_TYPE,  FORMAT_GEO_MAP,
              MAP_FRAME_PEN,  MAP_FRAME_WIDTH, MAP_GRID_CROSS_SIZE_PRIMARY, MAP_GRID_PEN_PRIMARY,
              MAP_GRID_CROSS_SIZE_SECONDARY,  MAP_GRID_PEN_SECONDARY,   FONT_TITLE,   FONT_LABEL,
              MAP_LINE_STEP,      MAP_ANNOT_OBLIQUE,      FORMAT_CLOCK_MAP,      FORMAT_DATE_MAP,
              FORMAT_TIME_PRIMARY_MAP, FORMAT_TIME_SECONDARY_MAP, GMT_LANGUAGE,  TIME_WEEK_START,
              MAP_TICK_LENGTH_PRIMARY,  and  MAP_TICK_PEN_PRIMARY;  see the gmt.conf man page for
              details.

   The -J option
       Syntax

       -Jparameters
              Specify the projection. (See cookbook summary) (See projections table).

       Description

       Select map projection. The first character of parameters determines the projection. If the
       character is upper case then the argument(s) supplied as scale(s) is interpreted to be the
       map width (or axis lengths), else  the  scale  argument(s)  is  the  map  scale  (see  its
       definition  for each projection). The measurement unit (called UNIT below) is cm, inch, or
       point, depending on the PROJ_LENGTH_UNIT setting in gmt.conf, but this can  be  overridden
       on the command line by appending c, i, or p to the scale or width values. Append +dh, +du,
       or +dl to the given width if you instead want to set the map height, the  maximum  (upper)
       dimension,  or the minimum (lower) dimension, respectively [Default is +dw for width].  In
       case the central meridian is an optional parameter and  it  is  being  omitted,  then  the
       center  of  the  longitude  range  given  by  the  -R option is used. The default standard
       parallel is the equator.  The ellipsoid used in  map  projections  is  user-definable.  73
       commonly used ellipsoids and spheroids are currently supported, and users may also specify
       their own custom ellipsoid parameters [Default is WGS-84].   Several  GMT  parameters  can
       affect   the   projection:   PROJ_ELLIPSOID,   GMT_INTERPOLANT,   PROJ_SCALE_FACTOR,   and
       PROJ_LENGTH_UNIT; see the gmt.conf man page for details.   Choose  one  of  the  following
       projections  and  append the required parameters (The E or C after projection names stands
       for Equal-Area and Conformal, respectively):
          CYLINDRICAL PROJECTIONS:
          -Jc|Clon0/lat0/scale|width (Cassini).
              Give projection  center  lon0/lat0  and  either  scale  (with  -Jc;  as  1:xxxx  or
              plot-units/degree) or width (with -JC; in plot-units).
          -Jcyl_stere|Cyl_stere/[lon0/[lat0/]]scale|width (Cylindrical Stereographic)
              Give  central  meridian  lon0  (optional),  standard  parallel lat0 (optional), and
              either scale along parallel (with -Jcyl_stere; as 1:xxxx or  plot-units/degree)  or
              width  (with -JCyc_stere; in plot-units). The standard parallel is typically one of
              these (but can be any value):

                 • 66.159467 - Miller’s modified Gall

                 • 55 - Kamenetskiy’s First

                 • 45 - Gall’s Stereographic

                 • 30 - Bolshoi Sovietskii Atlas Mira or Kamenetskiy’s Second

                 • 0 - Braun’s Cylindrical
          -Jj|J[lon0/]scale|width (Miller Cylindrical Projection).
              Give the central meridian lon0 (optional) and either scale (with -Jj; as 1:xxxx  or
              plot-units/degree) or width (with -JJ; in plot-units).
          -Jm|M[lon0/[lat0/]]scale|width (Mercator [C])
              Give  central  meridian  lon0  (optional),  standard  parallel lat0 (optional), and
              either scale along parallel (with -Jm; as 1:xxxx  or  plot-units/degree)  or  width
              (with -JM; in plot-units).
          -Joparameters[+v] (Oblique Mercator [C]).
              Typically used with -RLLx/LLy/URx/URy+r or with projected coordinates.  Specify one
              of:

              -Jo|O[a|A]lon0/lat0/azimuth/scale|width[+v]
                     Set projection center lon0/lat0, azimuth of oblique equator,  and  scale  or
                     width

              -Jo|O[b|B]lon0/lat0/lon1/lat1/scale|width[+v]
                     Set  projection  center  lon0/lat0,  another  point  on  the oblique equator
                     lon1/lat1, and scale or width

              -Jo|O[c|C]lon0/lat0/lonp/latp/scale|width[+v]
                     Set projection center lon0/lat0, pole of oblique projection  lonp/latp,  and
                     scale or width

              Give  scale  along  oblique  equator (with -Ja|b|c; 1:xxxx or plot-units/degree) or
              width (with -JA|B|C; in plot-units). Use upper-case A|B|C to remove enforcement  of
              a  northern  hemisphere  pole.  Append +v to let the oblique Equator align with the
              y-axis [x-axis].  Note: If the region (-R) is given without the  +r  modifier  then
              the  arguments are considered oblique degrees relative to the projection center and
              not longitude/latitude bounds.
          -Jq|Q[lon0/[lat0/]]scale|width (Cylindrical Equidistant).
              Give the central meridian lon0 (optional), standard parallel lat0  (optional),  and
              either  scale  (with  -Jq;  as  1:xxxx or plot-units/degree) or width (with -JQ; in
              plot-units) The standard parallel is typically one of these (but can be any value):

                 • 61.7 - Grafarend and Niermann, minimum linear distortion

                 • 50.5 - Ronald Miller Equirectangular

                 • 43.5 - Ronald Miller, minimum continental distortion

                 • 42 - Grafarend and Niermann

                 • 37.5 - Ronald Miller, minimum overall distortion

                 • 0 - Plate Carree, Simple Cylindrical, Plain/Plane Chart
          -Jt|Tlon0/[lat0/]scale|width (Transverse Mercator [C])
              Give the central meridian lon0, central parallel lat0 (optional), and either  scale
              (with -Jt; as 1:xxxx or plot-units/degree) or width (with -JT; in plot-units).
          -Ju|Uzone/scale|width (UTM - Universal Transverse Mercator [C]).
              Give  the  UTM  zone  (A,B,1-60[C-X],Y,Z)) and either scale (with -Ju; as 1:xxxx or
              plot-units/degree) or width (with -JU; in plot-units). Zones:  If  C-X  not  given,
              prepend  -  or + to enforce southern or northern hemisphere conventions [default is
              northern if south > 0].
          -Jy|Y[lon0/[lat0/]]scale|width (Cylindrical Equal-Area [E]).
              Give the central meridian lon0 (optional), standard parallel lat0  (optional),  and
              either  scale  (with  -Jy;  as  1:xxxx or plot-units/degree) or width (with -JY; in
              plot-units). The standard parallel is typically  one  of  these  (but  can  be  any
              value):

                 • 50 - Balthasart

                 • 45 - Gall

                 • 37.0666 - Caster

                 • 37.4 - Trystan Edwards

                 • 37.5 - Hobo-Dyer

                 • 30 - Behrman

                 • 0 - Lambert (default)

          CONIC PROJECTIONS:

          -Jb|Blon0/lat0/lat1/lat2/scale|width (Albers [E]).
                 Give  projection  center lon0/lat0, two standard parallels lat1/lat2, and either
                 scale (with -Jb;  as  1:xxxx  or  plot-units/degree)  or  width  (with  -JB;  in
                 plot-units).

          -Jd|Dlon0/lat0/lat1/lat2/scale|width (Conic Equidistant)
                 Give  projection  center lon0/lat0, two standard parallels lat1/lat2, and either
                 scale (with -Jd;  as  1:xxxx  or  plot-units/degree)  or  width  (with  -JD;  in
                 plot-units).

          -Jl|Llon0/lat0/lat1/lat2/scale|width (Lambert [C])
                 Give  origin  lon0/lat0, two standard parallels lat1/lat2, and scale along these
                 (with -Jl; as 1:xxxx or plot-units/degree) or width (with -JL; in plot-units).

          -Jpoly|Poly/[lon0/[lat0/]]scale|width ((American) Polyconic).
                 Give the central meridian lon0 (optional), reference  parallel  lat0  (optional,
                 default  =  equator),  and  either scale along central meridian (with -Jpoly; as
                 1:xxxx or plot-units/degree) or width (with -JPoly; in plot-units).

          AZIMUTHAL PROJECTIONS:

          Except   for   polar   aspects,   -Rw/e/s/n    will    be    reset    to    -Rg.    Use
          -Rxlleft/ylleft/xuright/yuright+r for smaller regions.

          -Ja|Alon0/lat0[/horizon]scale|width (Lambert [E]).
                 lon0/lat0  specifies  the  projection center. horizon specifies the max distance
                 from projection center (in degrees, <= 180, default 90). Give either scale (with
                 -Ja; as 1:xxxx or radius/lat, where radius is distance in plot-units from origin
                 to the oblique latitude lat) or width (with -JA; in plot-units).

          -Je|Elon0/lat0[/horizon]scale|width (Azimuthal Equidistant).
                 lon0/lat0 specifies the projection center. horizon specifies  the  max  distance
                 from  projection center (in degrees, <= 180, default 180). Give scale (with -Je;
                 as 1:xxxx or radius/lat, where radius is distance in plot-units from  origin  to
                 the oblique latitude lat) or width (with -JE; in plot-units).

          -Jf|Flon0/lat0[/horizon]scale|width (Gnomonic).
                 lon0/lat0  specifies  the  projection center. horizon specifies the max distance
                 from projection center (in degrees, < 90, default 60). Give scale (with -Jf;  as
                 1:xxxx  or radius/lat, where radius is distance in plot-units from origin to the
                 oblique latitude lat) or width (with -JF; in plot-units).

          -Jg|Glon0/lat0[/horizon]/scale|width (Orthographic).
                 lon0/lat0 specifies the projection center. horizon specifies  the  max  distance
                 from projection center (in degrees, <= 90, default 90). Give scale (with -Jg; as
                 1:xxxx or radius/lat, where radius is distance in plot-units from origin to  the
                 oblique latitude lat.

          -Jg|Glon0/lat0/scale|width[+aazimuth][+ttilt][+vvwidth/vheight][+wtwist][+zaltitude[r|R]|g]
          (General Perspective).
                     lon0/lat0 specifies the projection center. Give scale (with -Jg;  as  1:xxxx
                     or  radius/lat,  where  radius  is distance in plot-units from origin to the
                     oblique latitude lat) or width (with -JG; in plot-units).  Several  optional
                     modifiers control the perspective:

                 • +a sets azimuth measured to the east of north of view [0].

                 • +t  sets the upward tilt of the plane of projection. If tilt is negative, then
                   the viewpoint is centered on the horizon [0].

                 • +v sets a restricted view: vwidth and vheight ( in degrees)  limits  the  view
                   from the viewpoint [unrestricted].

                 • +w sets the clockwise twist of the viewpoint (in degrees) [0].

                 • +z  sets  the altitude of the viewer above sea level in kilometers [infinity].
                   Alternatively append R if giving the distance of the viewer from the center of
                   the  Earth  in Earth radii, or r if giving the distance from the center of the
                   Earth in kilometers.  Finally, give altitude as  g  to  compute  and  use  the
                   altitude for a geosynchronous orbit.

          -Js|Slon0/lat0[/horizon]/scale|width (General Stereographic [C]).
                 lon0/lat0  specifies  the  projection center. horizon specifies the max distance
                 from projection center (in degrees, < 180, default 90). Give scale (with -Js; as
                 1:xxxx  (true at pole) or lat/1:xxxx (true at standard parallel lat and requires
                 lat0 = ±90) or radius/lat (radius in  plot-units  from  origin  to  the  oblique
                 latitude  lat).  Note  if  1:xxxx  is used then to specify horizon you must also
                 specify the lat as ±90 to avoid ambiguity.) or width (with -JS; in plot-units).

          MISCELLANEOUS PROJECTIONS:

          -Jh|H[lon0/]scale|width (Hammer [E]).
                 Give the central meridian lon0 (optional) and either scale along  equator  (with
                 -Jh; as 1:xxxx or plot-units/degree) or width (with -JH; in plot-units).

          -Ji|I[lon0/]scale|width (Sinusoidal [E]).
                 Give  the  central meridian lon0 (optional) and either scale along equator (with
                 -Ji; as 1:xxxx or plot-units/degree) or width (with -JI; in plot-units).

          -Jk|Kf[lon0/]scale|width (Eckert IV [E]).
                 Give the central meridian lon0 (optional) and either scale along  equator  (with
                 -Jk; as 1:xxxx or plot-units/degree) or width (with -JK; in plot-units).

          -Jk|K[s][lon0/]scale|width (Eckert VI [E]).
                 Give  the  central meridian lon0 (optional) and either scale along equator (with
                 -Jk; as 1:xxxx or plot-units/degree) or width (with -JK; in plot-units).

          -Jn|N[lon0/]scale|width (Robinson).
                 Give the central meridian lon0 (optional) and either scale along  equator  (with
                 -Jn; as 1:xxxx or plot-units/degree) or width (with -JN; in plot-units).

          -Jr|R[lon0/]scale|width (Winkel Tripel).
                 Give  the  central meridian lon0 (optional) and either scale along equator (with
                 -Jr; as 1:xxxx or plot-units/degree) or width (with -JR; in plot-units).

          -Jv|V[lon0/]scale|width (Van der Grinten).
                 Give the central meridian lon0 (optional) and either scale along  equator  (with
                 -Jv; as 1:xxxx or plot-units/degree) or width (with -JV; in plot-units).

          -Jw|W[lon0/]scale|width (Mollweide [E]).
                 Give  the  central meridian lon0 (optional) and either scale along equator (with
                 -Jw; as 1:xxxx or plot-units/degree) or width (with -JW; in plot-units).

          NON-GEOGRAPHICAL PROJECTIONS:
          -Jp|Pscale|width[+a][+f[e|p|radius]][+kkind][+roffset][+torigin][+z[p|radius]]]  (Polar
          coordinates (theta, r))

          Give  scale  (with  -Jp;  in plot-units/r-unit) or width (with -JP; in plot-units). The
          following modifiers are supported by -Jp|P:

          • +a to indicate that theta is azimuth CW from North instead of direction CCW from East
            [Default is CCW from East].

          • +f  to  flip  the  radial direction to point inwards, and append e to indicate that r
            represents elevations in degrees (requires south >= 0 and north <= 90), p  to  select
            current planetary radius (determined by PROJ_ELLIPSOID) as maximum radius [north], or
            radius to specify a custom radius.

          • +k sets the annotation kind to  be  longitudes  (x)  or  latitudes  (y)  [Default  is
            unspecified angles].

          • +roffset to include a radial offset in measurement units [default is 0].

          • +torigin  in  degrees  so that this angular value is aligned with the positive x-axis
            (or the azimuth to be aligned with the positive y-axis if +a) [default is 0].

          • +z to annotate depth rather than radius [default is radius]. Alternatively, if your r
            data are actually depths then you can append p or radius to get radial annotations (r
            = radius - z) instead.
          -Jx|Xx-scale|width[l|ppower|T|t][/y-scale|height[l|ppower|T|t]][d|g] (Linear, log,  and
          power scaling)

          Give  x-scale  (with  -Jx;  as  1:xxxx  or plot-units/x-unit) and/or y-scale (1:xxxx or
          plot-units/y-unit);  or  specify  width  and/or  height  (with  -JX;  in   plot-units).
          y-scale=x-scale  if  not  specified separately and using 1:xxxx implies that x-unit and
          y-unit are in meters. Use negative scale(s) to reverse the direction of an axis  (e.g.,
          to  have  y  be positive down). Set height or width to 0 to have it recomputed based on
          the implied scale of the other axis.  Optionally, append to x-scale y-scale,  width  or
          height one of the following:

          • d to indicate that data are geographical coordinates (in degrees).

          • g to indicate that data are geographical coordinates

          • l to take log10 of values before scaling.

          • ppower to raise values to power before scaling.

          • t to indicate that input coordinates are time relative to TIME_EPOCH.

          • T to indicate that input coordinates are absolute time.
                For mixed axes with only one geographic axis you may need to set -f as well.

       When  -J  is  used  without  any  further arguments, or just with the projection type, the
       arguments of the last used -J, or the last used -J with  that  projection  type,  will  be
       used.

       -Jz|Zparameters
              Set z-axis scaling; same syntax as -Jx.

       -Jproj|EPSG:n
              Starting  at GMT6 it is possible to use the PROJ library to do coordinate and datum
              transforms.  This is achieved via the GDAL library.  It  is,  however,  beyond  the
              scope  of  this  manual to document the PROJ syntax (that is the syntax of the proj
              and cs2cs programs) so users are referred to PROJ Applications for the details.

              The usage of PROJ follows very closely the syntax of proj and cs2cs. The projection
              parameters are encapsulated under the -J option. Because there are normally several
              parameters defining a referencing system separated by spaces (in PROJ or  GDAL)  we
              can  either  use  double  quotes as in -J+proj=merc +ellps=WGS84 +units=m” or just
              glue all parameters like in -J+proj=merc+ellps=WGS84+units=m.

              Using EPSG  codes  is  also  possible  (but  need  the  setting  of  the  GDAL_DATA
              environment  variable  to  point  to  the  GDAL’s  data sub-directory). For example
              -JEPSG:4326 sets the WGS-84 system.

              For mapproject and grdproject we can go directly from the referencing system A to B
              without  the  intermediate  step  of converting to geographic coordinates.  That is
              obtained   (like   in   cs2cs)    by    using    the    +to    keyword.    Example:
              -JEPSG:4326+to+proj=aeqd+ellps=WGS84+units=m.  A much awaited bonus is also that we
              now do not need to set -R to do point coordinate conversions.

              While for point and grid conversions done by mapproject and grdproject we  can  use
              all  PROJ  projections, the situations is, however, rather more limited for mapping
              purposes.  Here, only the subset of the PROJ projections that can  be  mapped  into
              the  GMT projections syntax is available to use. Another aspect that is not present
              in PROJ, because it’s not a mapping library, is how to set the  map  scale  or  map
              dimension. We introduced the two extensions +width=size and +scale=1:xxxx that work
              exactly like the map width and scale in  classical  GMT.  It  is  also  allowed  to
              provide  the  scale (but NOT the width) by appending the string “/1:xxx” to the end
              of the projection parameters.

   The -R option
       Syntax

       -Rxmin/xmax/ymin/ymax[+r][+uunit]
              Specify the region of interest. (See cookbook information).

       Description

       The -R option defines the map region or data domain of interest. It may  be  specified  in
       one  of  several  ways  (options 1 and 3 are shown in panels a) and b) respectively of the
       Figure Map region):

       1. -Rxmin/xmax/ymin/ymax. This is the standard way to specify Cartesian data  domains  and
          geographic  regions  when  using  map  projections  where  meridians  and parallels are
          rectilinear, where xmin, xmax, ymin, and ymax refer to the data limits.

       2. -Rxmin/xmax/ymin/ymax+uunit. Append +uunit to the option  1  to  specify  a  region  in
          projected  units  (e.g.,  UTM meters) where xmin/xmax/ymin/ymax are Cartesian projected
          coordinates compatible with the chosen projection and unit  is  an  allowable  distance
          unit [e]. The coordinates are relative to the standard longitude and latitude indicated
          in the projection (-J).  For projected regions  centered  on  (0,0)  you  may  use  the
          short-hand  -Rhalfwidth[/halfheight]+uunit,  where  halfheight defaults to halfwidth if
          not given. This short-hand requires the +u modifier.

       3. -Rxlleft/ylleft/xuright/yuright+r. This form is useful for  map  projections  that  are
          oblique,  making  meridians  and  parallels  poor  choices for map boundaries. Here, we
          instead specify the lower left corner and upper right  corner  geographic  coordinates,
          followed  by  the modifier +r. This form guarantees a rectangular map even though lines
          of equal longitude and latitude are not straight lines.

       4. -Rg or -Rd. These forms can be used to quickly specify the global domain (0/360 for -Rg
          and -180/+180 for -Rd in longitude, with -90/+90 in latitude).

       5. -Rgridfile.  This  will  copy the domain settings found for the grid in specified file.
          Note that depending on the nature of the calling module, this mechanism will  also  set
          grid spacing and possibly the grid registration (see Grid registration: The -r option).

       6. -Rcode1,code2,…[+e|r|Rincs].  This indirectly supplies the region by consulting the DCW
          (Digital Chart of the World) database and derives the bounding regions for one or  more
          countries given by the codes. Simply append one or more comma-separated countries using
          either the two-character ISO 3166-1 alpha-2 convention (e.g., NO) or the  full  country
          name  (e.g.,  Norway). To select a state within a country (if available), append .state
          (e.g, US.TX), or the full state name (e.g., Texas). To specify a whole continent, spell
          out  the  full  continent  name  (e.g.,  -RAfrica).  Finally, append any DCW collection
          abbreviations or full names for the extent of the collection or named region. All names
          are case-insensitive. The following modifiers can be appended:

          • +r  to  adjust  the  region boundaries to be multiples of the steps indicated by inc,
            xinc/yinc, or winc/einc/sinc/ninc [default is no adjustment].  For  example,  -RFR+r1
            will  select  the  national bounding box of France rounded to nearest integer degree,
            where inc can be positive to expand the region or negative to shrink the region.

          • +R to adjust the region by  adding  the  amounts  specified  by  inc,  xinc/yinc,  or
            winc/einc/sinc/ninc  [default  is  no extension], where inc can be positive to expand
            the region or negative to shrink the region.

          • +e to adjust the region boundaries to be multiples of the  steps  indicated  by  inc,
            xinc/yinc,  or  winc/einc/sinc/ninc, while ensuring that the bounding box is adjusted
            by at least 0.25 times the increment [default is no adjustment],  where  inc  can  be
            positive to expand the region or negative to shrink the region.

       7. -Rjustifyx0/y0/nx/ny,  where  justify  is a 2-character combination of L|C|R (for left,
          center, or right) and T|M|B (for top, middle, or bottom) (e.g., BL for lower left). The
          two character code justify indicates which point on a rectangular grid region the x0/y0
          coordinates refer to and the grid dimensions nx and ny  are  used  with  grid  spacings
          given  via -I to create the corresponding region. This method can be used when creating
          grids. For example, -RCM25/25/50/50 specifies a 50x50 grid centered on 25,25.

       8. -Rxmin/xmax/ymin/ymax/zmin/zmax. This method can be used for perspective views with the
          -Jz and the -p option, where the z-range (zmin/zmax) is appended to the first method to
          indicate the third dimension. This is not used for -p without  -Jz,  in  which  case  a
          perspective view of the place is plotted with no third dimension.

       9. -Ra[uto]  or  -Re[xact].  Under  modern  mode,  and  for plotting modules only, you can
          automatically determine the region from the data used. You can  either  get  the  exact
          area  using  -Re [Default if no -R is given] or a slightly larger area sensibly rounded
          outwards to the next multiple of increments that depend on the data range using -Ra.
          In case of perspective view -p, a z-range (zmin, zmax) can be appended to indicate  the
          third  dimension.  This needs to be done only when using the -Jz option, not when using
          only the -p option. In the latter case a perspective view of the plane is plotted, with
          no third dimension.

   The -U option
       Syntax

       -U[label|+c][+jjust][+odx[/dy]]
              Draw GMT time stamp logo on plot. (See cookbook information).

       Description

       The  -U  option  draws  the GMT system time stamp on the plot. The following modifiers are
       supported:

       • label to append the text string given in label  (which  must  be  surrounded  by  double
         quotes if it contains spaces).

       • +c to plot the current command string.

       • +jjustify  to  specify  the  justification  of  the  time  stamp,  where  justify  is  a
         two-character justification  code  that  is  a  combination  of  a  horizontal  (L(eft),
         C(enter),  or  R(ight))  and  a vertical (T(op), M(iddle), or B(ottom)) code [default is
         BL].

       • +odx[/dy] to offset the anchor point for the time stamp by  dx  and  optionally  dy  (if
         different than dx).

       The  GMT parameters MAP_LOGO, MAP_LOGO_POS, FONT_LOGO and FORMAT_TIME_STAMP can affect the
       appearance; see the gmt.conf man page for details. The time string will be in  the  locale
       set by the environment variable TZ (generally local time).

   The -V option
       Syntax

       -V[level]
              Select verbosity level [w]. (See cookbook information).

       Description

       The  -V  option  controls  the verbosity mode, which determines which messages are sent to
       standard error. Choose among 7 levels of verbosity; each level adds more messages:

       • q - Quiet, not even fatal error messages are produced.

       • e - Error messages only.

       • w - Warnings (by default, same as running without -V)

       • t - Timings (report runtimes for time-intensive algorithms).

       • i - Informational messages (same as -V only).

       • c - Compatibility warnings (if compiled with backward-compatibility).

       • d - Debugging messages.

       This option can also be set  by  specifying  the  default  GMT_VERBOSE  as  quiet,  error,
       warning,  timing,  compat, information, or debug, in order of increased verbosity [default
       is warning].

   The -X -Y options
       Syntax

       -X[a|c|f|r][xshift]
              Shift plot origin. (See cookbook information).

       -Y[a|c|f|r][yshift]
              Shift plot origin. (See cookbook information).

       Description

       The -X  and  -Y  options  shift  the  plot  origin  relative  to  the  current  origin  by
       (xshift,yshift).  Optionally,  append  the  length  unit  (c,  i,  or  p).  Default  is (‐
       MAP_ORIGIN_X, MAP_ORIGIN_Y) for new plots, which ensures that boundary annotations fit  on
       the  page.  Subsequent  overlays  will  be co-registered with the previous plot unless the
       origin is shifted using these options. The following modifiers are supported  [default  is
       r]:

       • Prepend a to shift the origin back to the original position after plotting.

       • Prepend c to center the plot on the center of the paper (optionally add a shift).

       • Prepend f to shift the origin relative to the fixed lower left.

       • Prepend r to move the origin relative to its current location.

       When -X or -Y are used without any further arguments, the values from the last use of that
       option in a previous GMT command will be used. In modern mode, -X and -Y can  also  access
       the previous plot bounding box dimensions w and h and construct offsets that involve them.
       Thus, xshift can in general be [[±][f]w[/d]±]xoff, where  optional  signs,  factor  f  and
       divisor  d  can  be  used  to  compute  an  offset  that  may be adjusted further by ±off.
       Similarly, yshift can in general be [[±][f]h[/d]±]yoff.  For instance, to move the  origin
       up  2  cm beyond the height of the previous plot, use -Yh+2c.  To move the origin half the
       width to the right, use -Xw/2. Note: the previous plot bounding box  refers  to  the  last
       object plotted, which may be an image, logo, legend, colorbar, etc.

   The -a option
       Syntax

       -a[[col=]name][,]
              Control how aspatial data are handled in GMT during input and output.

       Description

       GMT  relies  on  external  tools  to  translate geospatial files such as shapefiles into a
       format we can read. The tool ogr2ogr in the GDAL package  can  do  such  translations  and
       preserve  the  aspatial  metadata via a new OGR/GMT format specification (See the cookbook
       chapter The GMT Vector Data Format for OGR Compatibility). For this to be useful we need a
       mechanism  to  associate  certain  metadata  values with required input and output columns
       expected by GMT programs. The -a option allows you to supply one or  more  comma-separated
       associations  col=name, where name is the name of an aspatial attribute field in a OGR/GMT
       file and whose value we wish to as data input for column col.  The  given  aspatial  field
       thus  replaces  any other value already set. Note: col = 0 is the first data column. Note:
       If no aspatial attributes are needed then the -a option is not needed  –  GMT  will  still
       process and read such data files.

   OGR/GMT input with -a option
       If  you  need  to  populate  GMT data columns with (constant) values specified by aspatial
       attributes, use -a and append any number of  comma-separated  col=name  associations.  For
       example,  -a2=depth  will  read  the spatial x,y columns from the file and add a third (z)
       column based on the value of the aspatial field  called  depth.  You  can  also  associate
       aspatial  fields  with  other  settings such as labels, fill colors, pens, and values (for
       looking-up colors) by letting the col value be one of D (for distance), G  (for  fill),  I
       (for  ID),  L  (for  label),  T  (for  text),  W  (for  pen), or Z (for value). This works
       analogously to how standard multi-segment files can pass  such  options  via  its  segment
       headers (See the cookbook chapter GMT File Formats). Note: If the leading col= is omitted,
       the column value is automatically incremented starting at 2.

   OGR/GMT output with -a option
       GMT table-writing tools can also output the OGR/GMT format directly.  Specify  if  certain
       GMT  data  columns  with  constant  values  should  be  stored  as aspatial metadata using
       col=name[:type], where you can optionally specify what data type it  should  be  from  the
       options  double,  float,  integer,  char,  string,  logical, byte, or datetime [default is
       double]. As for input, you can also use the special col entries of  D  (for  distance),  G
       (for fill), I (for ID), L (for label), T (for text), W (for pen), or Z (for value) to have
       values stored as options in segment headers be used as the source for the  named  aspatial
       field.  The  type  will  be  set automatically for these special col entries. Finally, for
       output you must append +ggeometry, where geometry can be any of [M]POINT|LINE|POLY;  where
       M  represents  the  multi-versions  of these three geometries. Use upper-case +G to signal
       that you want to split any line or polygon features that straddle the Dateline.

   The -bi option
       Syntax

       -birecord[+b|l]
              Select native binary format for primary table input (secondary  inputs  are  always
              ASCII).

       Description

       Select  native  binary  record  format  for primary table input. The record is one or more
       groups with format [ncols][type][w], where ncols is the number of consecutive data columns
       of given type and type must be one of:

          • c - int8_t (1-byte signed char)

          • u - uint8_t (1-byte unsigned char)

          • h - int16_t (2-byte signed int)

          • H - uint16_t (2-byte unsigned int)

          • i - int32_t (4-byte signed int)

          • I - uint32_t (4-byte unsigned int)

          • l - int64_t (8-byte signed int)

          • L - uint64_t (8-byte unsigned int)

          • f - 4-byte single-precision float

          • d - 8-byte double-precision float [Default]

          • x - use to skip ncols anywhere in the record

       Force  byte-swapping  of a group by appending w at the end of the group.  For records with
       mixed types, append additional comma-separated groups  (no  space  between  groups).   The
       following modifiers are supported:

          • +b|l  to  indicate that the entire data file should be read as big- or little-endian,
            respectively.

       The cumulative number of ncols may exceed the columns actually needed by the  program.  If
       ncols  is  not  specified  we  assume  that  type applies to all columns and that ncols is
       implied by the expectation of the program. When using native binary data the user must  be
       aware  of  the fact that GMT has no way of determining the actual number of columns in the
       file. Native binary files may have a header section, where the -h option can  be  used  to
       skip  the  first  n  bytes.  If  the  input file is netCDF, no -b is needed; simply append
       ?var1/var2/ to the filename to specify the variables to be read (see GMT File Formats and
       Modifiers  for  COARDS-compliant  netCDF  files for more information).  Here is an example
       that writes a binary file and reads it back with the first column 4 byte float, the second
       column 8 byte int, and the third column 8 byte double.

          echo 1.5 2 2.5 | gmt convert -bo1f,1l,1d > test.bin
          gmt convert test.bin -bi1f,1l,1d

   The -bo option
       Syntax

       -borecord[+b|l]
              Select native binary format for table output.

       Description

       Select  native  binary format for table output. The record must be one or more groups with
       format [ncols][type][w], where ncols is the number of consecutive data  columns  of  given
       type  and type must be one of c, u, h, H, i, I, l, L, f, or d [Default] (see -bi types for
       descriptions).  Force byte-swapping of a group by appending w at the  end  of  the  group.
       For a mixed-type output record, append additional comma-separated groups (no space between
       groups) The following modifiers are supported:

          • +b|l  to  indicate  that  the  entire  data  file  should  be  written  as  big-   or
            little-endian, respectively.

       If  ncols  is  not  specified we assume that type applies to all columns and that ncols is
       implied by the default output of the program. Note: NetCDF file output is not supported.

   The -c option
       Syntax

       -c[row,col|index]
              Advance to the selected subplot panel.

       Description

       The -c option can be used to either advance the focus of plotting to the next panel in the
       sequence (either by row or by column as set by subplot’s -A option) or to specify directly
       the row,col or 1-D index of the desired panel, when using  subplot  to  assemble  multiple
       individual panels in a matrix layout.  The -c option is only allowed when in subplot mode.
       If no -c option is given for the first subplot then we default to  row=col=index=0,  i.e.,
       the upper left panel.  Note: row, col, and index all start at 0.

   The -d option
       Syntax

       -di|onodata[+ccol]
              Substitute specific values with NaN.

       Description

       The  -d  option  allows  user-coded  missing  data values to be translated to official NaN
       values in GMT. Within GMT, any missing values are  represented  by  the  IEEE  NaN  value.
       However,  user  data  may  occasionally  denote missing data with an unlikely value (e.g.,
       -99999). Since GMT cannot guess this special missing data value, you can use the -d option
       to have such values replaced with NaNs. Similarly, the -d option can replace all NaNs with
       the chosed nodata value should the GMT output need to conform to such a requirement.

       For input only, use -dinodata to examine all input columns after the  first  two.  If  any
       item  equals  nodata,  the  value is interpreted as a missing data item and is substituted
       with the value NaN.

       For output only, use -donodata to examine all output columns. If any item equals NaN,  the
       NaN value is substituted with the chosen missing data value nodata.

       Use  the  +c  modifier  to  override  the starting column used for the examinations [2 for
       input, 0 for output].

   The -e option
       Syntax

       -e[~]“pattern” | -e[~]/regexp/[i]
              Only accept ASCII data records that contain the specified pattern.

       Description

       The -e option offers a built-in pattern scanner that will only pass records that match the
       given pattern or regular expressions, whereas modules that read ASCII tables will normally
       process all the data records that are read.  The test can also be inverted  to  only  pass
       data  records  that  do  not  match  the pattern, by using -e~. The test is not applied to
       header or segment headers. Should your pattern happen to start with ~  you  will  need  to
       escape  this  character  with a backslash [Default accepts all data records]. For matching
       data records against extended  regular  expressions,  please  enclose  the  expression  in
       slashes.  Append  i for case-insensitive matching. To supply a list of such patterns, give
       +ffile with one pattern per line.  To give a single pattern starting with  +f,  escape  it
       with a backslash.

   The -f option
       Syntax

       -f[i|o]colinfo
              Specify the data types of input and/or output columns (time or geographical data).

       Description

       The  -f  option  specifies what kind of data each input or output column contains when map
       projections are not required. Optionally, append i or o to make this apply only  to  input
       or  output,  respectively [Default applies to both]. Append a text string with information
       about each column (or range of columns) separated by commas. Each group  starts  with  the
       column  number  (0  is the first column) followed by either x (longitude), y (latitude), T
       (absolute calendar time), t (relative  time  in  chosen  TIME_UNIT  since  TIME_EPOCH),  d
       (dimension)  or s (trailing text). If several consecutive columns have the same format you
       may specify a range of columns rather than a single column. Column ranges must be given in
       the  format  start[:inc]:stop,  where inc defaults to 1 if not specified.  For example, if
       our input file has geographic coordinates (latitude,  longitude)  with  absolute  calendar
       coordinates  in  the columns 3 and 4, we would specify fi0y,1x,3:4T. All other columns are
       assumed to have the default (floating point) format and  need  not  be  set  individually.
       Note:  You  can  also  indicate that all items from the given column and to the end of the
       record should be considered trailing text by giving the code s (for string). Only the last
       group may set s. Note: Types T and s can only be used with ASCII data sets.

       Three  shorthand options for common selections are available. The shorthand -f[i|o]g means
       -f[i|o]0x,1y (i.e., geographic  coordinates),  while  -f[i|o]c  means  -f[i|o]0:1f  (i.e.,
       Cartesian  coordinates).  A special use of -f is to select -fp[unit], which requires -J -R
       and lets you use projected map  coordinates  (e.g.,  UTM  meters)  as  data  input.   Such
       coordinates  are  automatically  inverted  to  longitude, latitude during the data import.
       Optionally, append a length unit (see table distance units) [default is meter].  For  more
       information, see Sections Input data formats and Output data formats.

   The -g option
       Syntax

       -gx|y|z|d|X|Y|Dgap[u][+a][+ccol][+n|p]
              Examine  the  spacing  between consecutive data points in order to impose breaks in
              the line.

       Description

       The -g option is used to detect gaps based on one or more criteria. Repeat the  option  to
       specify  multiple  criteria.   A  criterion  is  specified  using one of the x|y|z|d|X|Y|D
       directives. The upper-case directives specify that the criterion should be applied to  the
       projected coordinates for modules that map data to map coordinates.

       • x|X  - define a gap when there is a large enough change in the x coordinates (upper case
         to use projected coordinates).

       • y|Y - define a gap when there is a large enough change in the y coordinates (upper  case
         to use projected coordinates).

       • z  - define a gap when there is a large enough change in the z data. Use +ccol to change
         the z data column [Default col is 2 (i.e., 3rd column)].

       • d|D - define a gap when there is a large enough distance between coordinates (upper case
         to use projected coordinates).

       A unit u may be appended to the specified gap:

       • For  geographic  data  (x|y|d), the unit may be arc d(egree), m(inute), and s(econd), or
         (m)e(ter), f(eet), k(ilometer), M(iles), or n(autical miles) [Default is (m)e(ter)].

       • For projected data (X|Y|D), the unit may be i(nch), c(entimeter),  or  p(oint)  [Default
         unit is set by PROJ_LENGTH_UNIT].

       Append modifier +a to specify that all the criteria must be met [default imposes breaks if
       any one criterion is met].

       One of the following modifiers can be appended:

       • +n - specify that the previous value minus the current column value must exceed gap  for
         a break to be imposed.

       • +p - specify that the current value minus the previous value must exceed gap for a break
         to be imposed.

       Default imposes breaks based on the absolute value of the difference between  the  current
       and  previous  value.   Note:  For  x|y|z with time data the unit is instead controlled by
       TIME_UNIT. Note: GMT has other mechanisms that can determine line segmentation,  including
       segments  defined  by  multiple  segment header records (see the cookbook chapter GMT File
       Formats) or segments defined by NaN values when IO_NAN_RECORDS is  set  to  pass  [default
       skips NaN values].

   The -h option
       Syntax

       -h[i|o][n][+c][+d][+msegheader][+rremark][+ttitle]
              Specify that input and/or output file(s) have n header records [default is 0].

       Description

       Specify  that  the  primary  input  file(s)  has n header record(s). The default number of
       header records is set by IO_N_HEADER_RECS [default is 0]. Use  -hi  if  only  the  primary
       input  data should have header records [Default will write out header records if the input
       data have them]. For output you may control the writing of header records using -h[o]  and
       the optional modifiers:

       • +d to remove existing header records.

       • +c to add a header comment with column names to the output [default is no column names].

       • +m to add a segment header segheader to the output after the header block [default is no
         segment header].

       • +r to add a remark comment to the output [default is no comment]. The remark string  may
         contain \n to indicate line-breaks.

       • +t  to  add  a  title  comment to the output [default is no title]. The title string may
         contain \n to indicate line-breaks.

       Note: Blank lines and lines starting with # are always skipped.  To  use  another  leading
       character for indicating header records, set IO_HEADER_MARKER. With -h in effect the first
       n records are taken verbatim as headers and not skipped even if any is  starting  with  #.
       Note: If used with native binary data (using -b) we interpret n to instead mean the number
       of bytes to skip on input or pad on output.

   The -i option
       Syntax

       -icols[+l][+ddivisor][+sscale|d|k][+ooffset][,][,t[word]]
              Select specific data columns for primary input, in arbitrary order.

       Description

       The -i option allows you to specify which input file physical data columns to use  and  in
       what  order.  Specify  individual columns or column ranges in the format start[:inc]:stop,
       where inc defaults to 1 if not specified, separated by commas [Default reads  all  columns
       in  order,  starting with the first column (i.e., column 0)]. Columns can be repeated. The
       chosen data columns will be used  as  given  and  columns  not  listed  will  be  skipped.
       Optionally,  append  one  of  the  following  modifiers  to  any column or column range to
       transform the input columns:

       • +l to take the log10 of the input values.

       • +d to divide the input values by the factor divisor [default is 1].

       • +s to multiply the input values by the factor scale [default is 1]. Alternatively,  give
         d to convert km to degrees or k to convert degrees to km using PROJ_MEAN_RADIUS.

       • +o to add the given offset to the input values [default is 0].

       Note: The order of these optional transformations are (1) take log10, (2) scale or divide,
       and (3) add offset.  To read from a given column until the end of the  record,  leave  off
       stop  when  specifying the column range. Normally, any trailing text will be read but when
       -i is used to specify specific input columns you must explicitly append the “column” t  to
       retain  the trailing text internally. To only ingest a single word from the trailing text,
       append the word number (first word is 0).  If your trailing  text  columns  start  with  a
       valid  number  and you want to ensure the content from column col to the end of the record
       will be considered trailing text, use -fcols.  Finally, -in will simply read the numerical
       input  and  skip  any  trailing  text.  Note: Using -i assumes there are as many numerical
       columns as implied in -i, so if you have a mix of numerical and text columns we will forge
       ahead and read those text columns (most likely returned as NaNs) and return your selection
       as numerical values.  The default (no -i  provided)  will  examine  the  record  and  stop
       conversions when the record switches to trailing text.

   The -j option (spherical distance calculations)
       Syntax

       -je|f|g
              Determine  how  spherical  distances  are  calculated  in modules that support this
              [Default is -jg].

       Description

       GMT has different ways to compute distances on planetary bodies:

       • -jg to perform great circle distance calculations,  with  parameters  such  as  distance
         increments or radii compared against calculated great circle distances [Default is -jg].

       • -jf to select Flat Earth mode, which gives a more approximate but faster result.

       • -je  to  select  ellipsoidal  (or  geodesic)  mode for the highest precision and slowest
         calculation time.

       Note:  All  spherical  distance  calculations  depend  on   the   current   ellipsoid   (‐
       PROJ_ELLIPSOID),   the   definition   of  the  mean  radius  (PROJ_MEAN_RADIUS),  and  the
       specification of latitude type (PROJ_AUX_LATITUDE).   Geodesic  distance  calculations  is
       also controlled by method (PROJ_GEODESIC).

   The -l option
       Syntax

       -l[label][+Dpen][+Ggap][+Hheader][+L[code/]text][+Ncols][+Ssize[/height]][+V[pen]][+ffont][+gfill][+jjustify][+ooff][+ppen][+sscale][+wwidth]
          Add a map legend entry to the session legend information file for the current plot.

       Description

       The -l option is used to automatically build the specfile  that  is  read  by  the  legend
       module  to  create  map or plot legends. This allows detailed and complicated legends that
       mix a variety of items, such as symbols, free text, colorbars, scales, images,  and  more.
       Yet,  a  simple  legend  will suffice for the vast majority of plots displaying symbols or
       lines. Optionally, append a text label to describe the entry. The following modifiers  are
       supported  to  allow  further  changes  to  the legend that is built by legend (upper-case
       modifiers reflect legend codes described  in  legend,  which  provides  more  details  and
       customization):

       • +D to draw a horizontal line in the given pen before the legend entry is placed [default
         is no line].

       • +G to add the vertical space specified by gap [default is no extra space].

       • +H to add the specified legend header [default is no header].

       • +L to set a line text. Optionally,  prepend  a  horizontal  justification  code  L(eft),
         C(enter), or R(ight) for text [default is C].

       • +N  to  change  the  number  of  columns  used to set the following legend items to cols
         [default is 1].

       • +S to override the size of the current symbol for the legend or set a height if plotting
         a line or contour [default uses the same symbol as plotted].

       • +V  to start and +vpen to stop drawing vertical line from previous to current horizontal
         line [default is no vertical line].

       • +f to set the font used for the legend header [default is FONT_TITLE].

       • +g to set the fill used for the legend frame [default is white].

       • +j to set placement of the legend using the  two-character  justification  code  justify
         [default is TR].

       • +o to set the offset from legend frame to anchor point [default is 0.2c].

       • +p to set the pen used for the legend frame [default is 1p].

       • +s to resize all symbol and length sizes in the legend by scale [default is no scaling].

       • +w to set legend frame width [default is auto].

       Note:  Default  pen is given by MAP_DEFAULT_PEN. Note: +H, +g, +j, +o, +p, +w, and +s will
       only take effect if appended to the very first -l option for a plot. The +N  modifier,  if
       appended  to  the first -l option, affects the legend width (unless set via +w); otherwise
       it just subdivides the available width among the  specified  columns.  If  legend  is  not
       called  explicitly  we  will  call it implicitly when finishing the plot via end. Note: If
       auto-coloring is used for pens or fills and -l is set then label may  contain  a  C-format
       for  integers  (e.g., %3.3d) or just # and we will use the sequence number with the format
       to build the label entries.  Alternatively, give a list of comma-separated labels, or give
       no  label  if your segment headers contain label settings. Note: Due to this mechanism, if
       your single label actually contains commas, you must replace these with the octal code for
       a comma (\054).

   The -n option
       Syntax

       -n[b|c|l|n][+a][+bg|p|n][+c][+tthreshold]
              Select grid interpolation mode.

       Description

       The  -n  option  controls  parameters  used  for  2-D grids resampling [default is bicubic
       interpolation with antialiasing and a threshold of 0.5, using geographic (if grid is known
       to  be  geographic) or natural boundary conditions]. Append one of the following to select
       the type of spline used:

       • b to use B-spline smoothing.

       • c to use bicubic interpolation.

       • l to use bilinear interpolation.

       • n to use nearest-neighbor value (for example to plot categorical data).

       The following modifiers are supported:

       • +a to switch off antialiasing (where supported) [default uses antialiasing].

       • +b to override boundary conditions used, by appending g for geographic, p for  periodic,
         or  n  for  natural  boundary  conditions.  For  the latter two you may append x or y to
         specify just one direction, otherwise both are assumed.

       • +c to clip the interpolated grid to input z-min/z-max [default may exceed limits].

       • +t to control how close to nodes with NaNs the interpolation will go based on threshold.
         A threshold of 1.0 requires all (4 or 16) nodes involved in interpolation to be non-NaN.
         For example, 0.5 will interpolate about half way from a non-NaN value and  0.1  will  go
         about 90% of the way [default is 0.5].

   The -o option
       Syntax

       -ocols[,…][,t[word]]
              Select specific data columns for primary output, in arbitrary order.

       Description

       The  -o option allows you to specify which output file physical data columns to use and in
       what order. Specify individual columns or column ranges in  the  format  start[:inc]:stop,
       where  inc defaults to 1 if not specified, separated by commas [Default writes all columns
       in order, starting with the first column (i.e., column 0)]. Columns can be  repeated.  The
       chosen data columns will be used as given and columns not listed will be skipped. To write
       from a given column until the end of the record, leave off stop when specifying the column
       range.

       Normally,  any  trailing  text in the internal records will be included in the output, but
       when -o is used to specify specific columns you must explicitly append the extra  “column”
       t  to  include the trailing text on output. To only select a single word from the trailing
       text, append the word number (first word is  0).   Finally,  -on  will  simply  write  the
       numerical  output only and skip any trailing text, while -ot will only output the trailing
       text (or selected word). Note: If -i is also used then columns given to -o  correspond  to
       the  order  after  the  -i  selection  has taken place and not the columns in the original
       record.

   The -p option
       Syntax

       -p[x|y|z]azim[/elev[/zlevel]][+wlon0/lat0[/z0]][+vx0/y0]
              Select perspective view and set the azimuth and elevation of the viewpoint.

       Description

       All plotting programs that normally produce a flat, two-dimensional  illustration  can  be
       told  to  view  this  flat  illustration  from  a particular vantage point, resulting in a
       perspective view. You can select perspective view  with  the  -p  option  by  setting  the
       azimuth (azim) of the viewpoint [Default is 180]. The following modifiers are supported:

       • x|y|z  to  plot  against  the  “wall”  x = level (using x) or y = level (using y) or the
         horizontal plain (using z) [default is z].

       • /elev to set the elevation of the viewport [Default is 90].

       • /zlevel to indicate the z-level at which all  2D  material,  like  the  plot  frame,  is
         plotted  (only  valid  when  -p  is  used in consort with -Jz or -JZ) [Default is at the
         bottom of the z-axis].

       For frames used for animation, we fix the center of  your  data  domain.  Specify  another
       center using one of the following modifiers:

       • +w to project lon0/lat0 (and z0 if applicable) to the center of the page size.

       • +v to specify the coordinates of the projected 2-D view point as x0/y0.

       When  -p  is  used  without any further arguments, the values from the last use of -p in a
       previous GMT command will be used (in modern mode this also supplies the previous  -Jz  or
       -JZ  if  doing  a  3-D region). Alternatively, you can perform a simple rotation about the
       z-axis by just giving the rotation angle. Optionally, use +v or +w to select another  axis
       location than the plot origin.

   The -q option
       Syntax

       -q[i|o][~]rows|limits[+ccol][+a|t|s]
              Select specific data rows to be read and/or written.

       Description

       The -q option is used to select specific data rows to be read (using -q or -qi) or written
       (using -qo) [Default is all rows]. Specify individual rows or row  ranges  in  the  format
       start[:inc]:stop,  where  inc defaults to 1 if not specified, separated by commas [Default
       reads and writes all rows in order, starting with the first row (i.e., row  0)].  To  read
       (or  write)  from a given row until the end of the data, leave off stop. To select all the
       rows not specified by the given ranges, prepend the selected rows with a leading ~. Append
       one of the following modifiers to control how the rows are counted [Default is +a]:

       • +a to count all rows in the data set.

       • +t to reset the count at the start of each table.

       • +s to reset the count at the start of each segment.

       Alternatively,  use  +ccol  to indicate that the arguments instead are min/max data limits
       for the values in column col. With +ccol, only rows whose data for the  given  column  col
       are  within  the range(s) given by the min/max limits are read (with -qi) or written (with
       -qo). Note: Because arguments may contain colons or be negative, you must specify  min/max
       instead  of  start[:inc]:stop.  If  min  or max is not given we default to -infinity and +
       infinity, respectively (e.g., -qo50/+c2 will only write records  whose  z-values  (in  3rd
       column) is ≥ 50 while -qo/50+c2 will only write records whose z-values is ≤ 50).

       Note: Header records do not increase the row counters; only data records do.

   The -r option (grid registration)
       Syntax

       -r[g|p]
              Select gridline or pixel node registration.

       Description

       All  2-D grids in GMT have their nodes organized in one of two ways, known as gridline and
       pixel registration. The GMT default is gridline registration (-rg);  programs  that  allow
       for  the  creation  of  grids  can use the -r option (or -rp) to select pixel registration
       instead.

       Most observed data tend to be in gridline registration while processed data  sometime  may
       be distributed in pixel registration.  While you may convert between the two registrations
       this conversion looses the Nyquist frequency and dampens the other high frequencies. It is
       best  to  avoid  any  registration  conversion  if  you can help it. Planning ahead may be
       important. (Node registrations are defined in Section Grid registration: The -r option  of
       the GMT Technical Reference and Cookbook.)

   The -s option
       Syntax

       -s[cols][+a][+r]
              Suppress output of data records whose z-value(s) equal NaN.

       Description

       The -s option can be used to suppress output for records whose z-value equals NaN [default
       outputs all records].  Optionally, supply a comma-separated list of all columns or  column
       ranges  to consider for this NaN test [default only considers the third data column (i.e.,
       cols = 2)]. Column ranges must be given in the format start[:inc]:stop, where inc defaults
       to 1 if not specified. The following modifiers are supported:

       • +r to reverse the suppression, i.e., only output the records whose z-value equals NaN.

       • +a  to  suppress  the  output of the record if just one or more of the columns equal NaN
         [default skips record only if values in all specified cols equal NaN]

   The -t option
       Syntax

       -ttransp[/transp2][+f|s]
              Set transparency level(s) for an overlay.

       Description

       The -t option allows you to change the transparency  level  for  the  current  overlay  by
       appending  the  transp  percentage  in  the  0-100  range  [default  is 0 (i.e., opaque)].
       Normally, transp applies to both fill and stroke, but you can limit  the  transparency  to
       one  of them by appending +f or +s for fill or stroke, respectively. Alternatively, append
       /transp2 to set separate transparencies for fills and strokes.

       Transparency may also be controlled on a feature by feature basis when  setting  color  or
       fill  (see  the cookbook section Specifying area fill attributes). Note: The modules plot,
       plot3d, and text can all change transparency on a record-by-record basis if  -t  is  given
       without argument and the input file supplies variable transparencies as the last numerical
       column value(s). Note: The transparency is only visible when PDF or raster  format  output
       is  selected  because  the PostScript language does not support transparency. Only the PNG
       format selection adds a transparency layer in the image (for further processing).

   The -w option
       Syntax

       -wy|a|w|d|h|m|s|cperiod[/phase][+ccol]
              Convert input records to a cyclical coordinate.

       Description

       The -w option converts the input x-coordinate to a cyclical  coordinate,  or  a  different
       input  column  if  selected via the +c modifier. Temporal data (i.e., regular time series)
       can be analyzed for periods via standard spectral analysis, such as offered by  spectrum1d
       and  grdfft.  However, it is often of interest to examine aspects of such periodicities in
       the time domain.  To enable such analyses we need to convert our monotonically  increasing
       time  coordinates  to  periodic or cyclic coordinates so that data from many cycles can be
       stacked, binned, displayed in histograms, etc. The  conversion  from  input  x,  y,  or  z
       coordinates to wrapped, periodic coordinates follows the simple equation

                                  t' = (t - \tau) \;\mathrm{mod}\; T,

       where  t  is  the  input coordinate, \tau is a phase-shift [Default is zero], and T is the
       desired period for the modulus operator, yielding cyclic coordinates t'. GMT  offers  many
       standard  time cycles in prescribed units plus a custom cycle for other types of Cartesian
       coordinates. The table below shows the  values  for  units,  phase  and  period  that  are
       prescribed  and  only  requires  the  user  to  specify  the  corresponding  wrapping code
       (y|a|w|d|h|m|s|cperiod[/phase]):

                          ┌─────┬──────────────────┬──────────┬───────┬───────┐
                          │CodePurpose (unit)   │ PeriodPhaseRange │
                          ├─────┼──────────────────┼──────────┼───────┼───────┤
                          │y    │ Yearly     cycle │ 1 year   │ 0     │ 0–1   │
                          │     │ (normalized)     │          │       │       │
                          ├─────┼──────────────────┼──────────┼───────┼───────┤
                          │a    │ Annual     cycle │ 1 year   │ 0     │ 0–12  │
                          │     │ (month)          │          │       │       │
                          ├─────┼──────────────────┼──────────┼───────┼───────┤
                          │w    │ Weekly     cycle │ 1 week   │ 0     │ 0–7   │
                          │     │ (day)            │          │       │       │
                          ├─────┼──────────────────┼──────────┼───────┼───────┤
                          │d    │ Daily      cycle │ 1 day    │ 0     │ 0–24  │
                          │     │ (hour)           │          │       │       │
                          ├─────┼──────────────────┼──────────┼───────┼───────┤
                          │h    │ Hourly     cycle │ 1 hour   │ 0     │ 0–60  │
                          │     │ (minute)         │          │       │       │
                          ├─────┼──────────────────┼──────────┼───────┼───────┤
                          │m    │ Minute     cycle │ 1 minute │ 0     │ 0–60  │
                          │     │ (second)         │          │       │       │
                          ├─────┼──────────────────┼──────────┼───────┼───────┤
                          │s    │ Second     cycle │ 1 second │ 0     │ 0–1   │
                          │     │ (second)         │          │       │       │
                          ├─────┼──────────────────┼──────────┼───────┼───────┤
                          │c    │ Custom     cycle │ T        │ \tau  │ 0–1   │
                          │     │ (normalized)     │          │       │       │
                          └─────┴──────────────────┴──────────┴───────┴───────┘

       Optionally, append +ccol to select the input column with the coordinates  to  be  wrapped,
       [default  col is 0, i.e., the first column]. If the custom cycle c is chosen then you must
       also supply the period and optionally any phase [default is 0] in the same units  of  your
       data (i.e., no units should be appended to -w).

       Note:  Coordinates for w in the range 0-1 correspond to the first day of the week [Monday]
       but can be changed via TIME_WEEK_START. Note: If a temporal cycle  is  indicated  then  we
       implicitly  set  -f  to  indicate  absolute  time (unless already set separately). See the
       cookbook section Examining data cycles: The -w option for examples.

   The -x option
       Syntax

       -x[[-]n]
              Specify the number of active cores to be used in any OpenMP-enabled  multi-threaded
              algorithms.

       Description

       The  -x  option limits the number of cores to be used in any OpenMP-enabled multi-threaded
       algorithms [default is to use all available cores]. Append n to only use n cores  (if  too
       large it will be truncated to the maximum cores available).  Finally, give a negative n to
       select (all - n) cores (or at least 1 if n equals or exceeds all).  The -x option is  only
       available  to  GMT  modules  compiled with OpenMP support, with the exception of movie and
       batch which handle their own parallel execution.

   The -: option
       Syntax

       -:[i|o]
              Swap 1st and 2nd column on input and/or output.

       Description The -: option swaps the 1st and 2nd column on input and output [default is  no
       swapping].  Append  i  to  select  input  only or o to select output only [default affects
       both]. This option is typically used to handle (latitude, longitude) files; see also Input
       columns  selection:  The  -i  option.  Note  that  command  line  arguments  that may take
       geographic  coordinates  (e.g.,  -R)  always  expect  longitude  before  latitude.   Also,
       geographical grids are expected to have the longitude as first (minor) dimension.

   Module help and configuration
       -^ or just -
              Print  a short message about the syntax of the command, then exit (Note: on Windows
              just use -).

       -+ or just +
              Print  an  extensive  usage  (help)  message,  including  the  explanation  of  any
              module-specific option (but not the GMT common options), then exit.

       -? or no arguments
              Print  a  complete  usage (help) message, including the explanation of all options,
              then exit.

       --PAR=value
              Temporarily  override  a  GMT  default  setting;  repeatable.  See   gmt.conf   for
              parameters.

   Specifying Color
       color  The color of lines, areas and patterns can be specified by a valid color name, by a
              gray shade (in the range 0-255), by a decimal color triplet RGB (r/g/b, each in the
              range  0–255), by hue-saturation-value HSV (h-s-v, with ranges of 0-360, 0-1, 0-1),
              by cyan/magenta/yellow/black CMYK (c/m/y/k,  each  in  the  range  0-1),  or  by  a
              hexadecimal  color  code  (#rrggbb,  as  used  in HTML). For a transparency effect,
              append @transparency in the 0–100 percent  range  [Default  is  0  (opaque)]  Note:
              Transparency  effects  are  only  visible  when  PDF or a raster graphics format is
              selected.  See Explanation of color codes in GMT for more information  and  a  full
              list of color names.

   Specifying Fill
       fill   The  attribute  fill specifies the solid shade or solid color (see Specifying Color
              above) or the pattern  used  for  filling  polygons.   Patterns  are  specified  as
              ppattern,  where  pattern set the number of the built-in pattern (1-90) or the name
              of a raster image file. The optional +rdpi sets the resolution of the image  [300].
              For  1-bit  rasters:  use upper case P  for inverse video, or append +fcolor and/or
              +bcolor to specify fore- and background colors (no color given means transparency).
              See  Predefined  Bit  and  Hachure  Patterns  in  GMT for information on individual
              built-in patterns.

   Specifying Fonts
       font   The attributes of text fonts as defined by font is a comma delimited list of  size,
              fonttype  and  fill,  each  of which is optional. size is the font size (usually in
              points) but c or i can be added to indicate other units. fonttype is the name (case
              sensitive!) of the font or its equivalent numerical ID (e.g., Helvetica-Bold or 1).
              fill specifies the gray shade, color or pattern of the text  (see  Specifying  Fill
              above).  Optionally,  you may append =pen to the fill value in order to draw a text
              outline. If you want to avoid that the outline partially obscures the text,  append
              =~pen  instead;  in  that case only half the linewidth is plotted on the outside of
              the font only.  If an outline is requested, you may optionally skip the  text  fill
              by  setting it to -, in which case the full pen width is always used. If any of the
              font attributes is omitted their default or previous setting will be retained.

              The 35 available fonts (plus 4 optional Japanese fonts) are:

              0.   Helvetica

              1.   Helvetica-Bold

              2.   Helvetica-Oblique

              3.   Helvetica-BoldOblique

              4.   Times-Roman

              5.   Times-Bold

              6.   Times-Italic

              7.   Times-BoldItalic

              8.   Courier

              9.   Courier-Bold

              10.  Courier-Oblique

              11.  Courier-BoldOblique

              12.  Symbol

              13.  AvantGarde-Book

              14.  AvantGarde-BookOblique

              15.  AvantGarde-Demi

              16.  AvantGarde-DemiOblique

              17.  Bookman-Demi

              18.  Bookman-DemiItalic

              19.  Bookman-Light

              20.  Bookman-LightItalic

              21.  Helvetica-Narrow

              22.  Helvetica-Narrow-Bold

              23.  Helvetica-Narrow-Oblique

              24.  Helvetica-Narrow-BoldOblique

              25.  NewCenturySchlbk-Roman

              26.  NewCenturySchlbk-Italic

              27.  NewCenturySchlbk-Bold

              28.  NewCenturySchlbk-BoldItalic

              29.  Palatino-Roman

              30.  Palatino-Italic

              31.  Palatino-Bold

              32.  Palatino-BoldItalic

              33.  ZapfChancery-MediumItalic

              34.  ZapfDingbats

              35.  Ryumin-Light-EUC-H

              36.  Ryumin-Light-EUC-V

              37.  GothicBBB-Medium-EUC-H

              38.  GothicBBB-Medium-EUC-V

   Specifying Pens
       pen    The attributes of lines and symbol outlines as defined by pen is a  comma-delimited
              list  of  width, color and style, each of which is optional. width can be indicated
              as a measure (in points (this is the default), centimeters, or inches) or as faint,
              default,  thin[ner|nest],  thick[er|est], fat[ter|test], or wide. color specifies a
              gray shade or color (see Specifying Color above). style  can  be  any  of  ‘solid’,
              ‘dashed’  ‘dotted’,  ‘dashdot’, or ‘dotdash’, or a custom combination of dashes ‘-’
              and dots ‘.’. If any of the attributes is omitted their default or previous setting
              will  be retained. See GMT Cookbook & Technical Reference Specifying pen attributes
              for more information.

ASCII FORMAT PRECISION

       The ASCII output formats of numerical data are controlled by parameters in  your  gmt.conf
       file.  Longitude  and latitude are formatted according to FORMAT_GEO_OUT, absolute time is
       under the control of FORMAT_DATE_OUT and FORMAT_CLOCK_OUT, whereas general floating  point
       values are formatted according to FORMAT_FLOAT_OUT. Be aware that the format in effect can
       lead to loss of precision in ASCII output, which can lead to various problems  downstream.
       If  you find the output is not written with enough precision, consider switching to binary
       output (-bo if available) or specify more decimals using the FORMAT_FLOAT_OUT setting.

GRID FILE FORMATS

       By default GMT writes out grids as single precision floats in  a  COARDS-complaint  netCDF
       file  format.  However,  GMT is able to produce and read grid files in many other commonly
       used grid file formats and also facilitates so called  “packing”  of  grids,  writing  out
       floating  point data as 1- or 2-byte integers. To specify the precision, scale and offset,
       the user should add the suffix [=ID][+ddivisor][+ninvalid][+ooffset][+sscale], where ID is
       a two-letter identifier of the grid type and precision, and the scale (or divisor), offset
       and invalid are the arguments of optional modifiers to be  applied  to  all  grid  values,
       Here,  invalid is the value used to indicate missing data. In case the ID is not provided,
       as in +sscale, then a ID=nf is assumed.  When  reading  grids,  the  format  is  generally
       automatically  recognized  from  almost  all  of  those formats that GMT and GDAL combined
       offer. If not, the same suffix can be added to input grid file names.  If reading an image
       as  a  grid  you  can select the band via +b.  See grdconvert and Section Grid file format
       specifications of the GMT Technical Reference and Cookbook for more information  regarding
       GDAL settings.

       When  reading  a  netCDF file that contains multiple grids, GMT will read, by default, the
       first 2-dimensional grid that it can find in that file. To coax GMT into  reading  another
       multi-dimensional  variable  in  the  grid  file,  append ?varname to the file name, where
       varname is the name of the variable. Note that you may need to escape the special  meaning
       of  ?  in  your  shell  program  by  putting a backslash in front of it, or by placing the
       filename and suffix between quotes or double quotes. The ?varname suffix can also be  used
       for  output  grids  to  specify  a  variable  name  different  from  the default: “z”. See
       grdconvert and Sections Modifiers for COARDS-compliant netCDF files and Grid  file  format
       specifications  of  the  GMT  Technical  Reference  and  Cookbook  for  more  information,
       particularly on how to read slices of 3-, 4-, or 5-dimensional grids.

       When writing a netCDF file, the grid is stored by default with the variable name  “z”.  To
       specify another variable name varname, append ?varname to the file name. Note that you may
       need to escape the special meaning of ? in your shell program by putting  a  backslash  in
       front of it, or by placing the filename and suffix between quotes or double quotes.

CLASSIC MODE OPTIONS

       These options are only used in classic mode and are listed here just for reference.

       -K     More  PostScript  code will be appended later [Default terminates the plot system].
              Required for all but the last plot command when building multi-layer plots.

       -O     Selects Overlay plot mode [Default initializes a new plot  system].   Required  for
              all but the first plot command when building multi-layer plots.

       -P     Select  “Portrait” plot orientation [Default is “Landscape”; see gmt.conf or gmtset
              to     change      the      PS_PAGE_ORIENTATION      parameter,      or      supply
              --PS_PAGE_ORIENTATION=orientation on the command line].

MORE INFORMATION SOURCES

       Look  up the individual man pages for more details and full syntax. Run gmt --help to list
       all GMT programs and to show all installation  directories.  For  an  explanation  of  the
       various GMT settings in this man page (like FORMAT_FLOAT_OUT), see the man page of the GMT
       configuration file gmt.conf. Information is also available on the GMT  documentation  site
       https://docs.generic-mapping-tools.org/

DEPRECATIONS

       • 6.3.0: Update -g syntax. #5617

       • 6.3.0: Update -JG syntax to use modifiers. #5780

SEE ALSO

       docs

COPYRIGHT

       2022, The GMT Team