Improved synopsis and usage of -Ccpt for grid plot modules (#8165)

* Improve synopsis and usage of -Ccpt for grid*-plotters

The grid plotters grd2kml, grdimage, grdview, and grdvector takes a bit more complicated CPT argument.  This is not documented better via API function gmt_explain_cpt_input and RST include file use_cpt_grd.rst_
Also fixed up synopsis syntax via constant CPT_OPT_ARGS.

* More polish

Ensure Unit link is employed in those 5 files.

* Update gmt_support.c

doc/rst/source/grd2kml.rst

@@ -15,7 +15,7 @@ Synopsis
 **gmt grd2kml** *ingrid*
 |-N|\ *prefix*
 [ |-A|\ **a**\|\ **g**\|\ **s**\ [*altitude*] ]
-[ |-C|\ *cpt* ]
+[ |-C|\ [*section*/]\ *master*\|\ *cpt*\|\ *color*\ :math:`_1`,\ *color*\ :math:`_2`\ [,\ *color*\ :math:`_3`\ ,...]\ [**+h**\ [*hinge*]][**+i**\ *dz*][**+u**\|\ **U**\ *unit*][**+s**\ *fname*] ]
 [ |-E|\ *URL* ]
 [ |-F|\ *filtercode* ]
 [ |-H|\ *scale* ]
@@ -153,6 +153,10 @@ Optional Arguments
 
 .. include:: explain_-n.rst_
 
+.. include:: explain_help.rst_
+
+.. include:: explain_distunits.rst_
+
 Quadtree building
 -----------------
 

doc/rst/source/grdimage.rst

@@ -16,7 +16,7 @@ Synopsis
 |-J|\ *parameters*
 [ |-A|\ *out_img*\ [**=**\ *driver*] ]
 [ |SYN_OPT-B| ]
-[ |-C|\ *cpt* ]
+[ |-C|\ [*section*/]\ *master*\|\ *cpt*\|\ *color*\ :math:`_1`,\ *color*\ :math:`_2`\ [,\ *color*\ :math:`_3`\ ,...]\ [**+h**\ [*hinge*]][**+i**\ *dz*][**+u**\|\ **U**\ *unit*][**+s**\ *fname*] ]
 [ |-D|\ [**r**] ]
 [ |-E|\ [**i**\|\ *dpi*] ]
 [ |-G|\ *color*\ [**+b**\|\ **f**] ]
@@ -216,6 +216,8 @@ Optional Arguments
 
 .. include:: explain_help.rst_
 
+.. include:: explain_distunits.rst_
+
 .. module_common_ends
 
 .. module_note_begins

doc/rst/source/grdvector.rst

@@ -15,7 +15,7 @@ Synopsis
 **gmt grdvector** *grid1* *grid2* |-J|\ *parameters*
 [ |-A| ]
 [ |SYN_OPT-B| ]
-[ |-C|\ *cpt* ]
+[ |-C|\ [*section*/]\ *master*\|\ *cpt*\|\ *color*\ :math:`_1`,\ *color*\ :math:`_2`\ [,\ *color*\ :math:`_3`\ ,...]\ [**+h**\ [*hinge*]][**+i**\ *dz*][**+u**\|\ **U**\ *unit*][**+s**\ *fname*] ]
 [ |-G|\ *fill* ]
 [ |-I|\ [**x**]\ *dx*\ [/*dy*] ]
 [ |-N| ] [ |-Q|\ *parameters* ]

doc/rst/source/grdview.rst

@@ -14,7 +14,7 @@ Synopsis
 
 **gmt grdview** *reliefgrid* |-J|\ *parameters*
 [ |SYN_OPT-B| ]
-[ |-C|\ [*cpt*]]
+[ |-C|\ [*section*/]\ *master*\|\ *cpt*\|\ *color*\ :math:`_1`,\ *color*\ :math:`_2`\ [,\ *color*\ :math:`_3`\ ,...]\ [**+h**\ [*hinge*]][**+i**\ *dz*][**+u**\|\ **U**\ *unit*][**+s**\ *fname*] ]
 [ |-G|\ *drapegrid* \| |-G|\ *grd_r* |-G|\ *grd_g* |-G|\ *grd_b* ]
 [ |-I|\ [*ifile*\|\ *intens*\|\ **+a**\ *azimuth*][**+d**][**+m**\ *ambient*][**+n**\ *args*] ]
 [ |-Jz|\ \|\ **Z**\ *parameters* ]
@@ -194,6 +194,8 @@ Optional Arguments
 
 .. include:: explain_help.rst_
 
+.. include:: explain_distunits.rst_
+
 .. include:: explain_grdresample.rst_
 
 .. module_common_ends

doc/rst/source/use_cpt_grd.rst_

@@ -1,27 +1,28 @@
-**-C**\ [[*section*/]\ *master_cpt*\ [**+h**\ [*hinge*]][**+u**\|\ **U**\ *unit*]\|\ *local.cpt*\|\ *color*\ :math:`_1`,\ *color*\ :math:`_2`\ [,\ *color*\ :math:`_3`\ ,...]][**+s**\ *fname*]]
-    Name of an input CPT file or a comma-separated list of colors from which to build a CPT.
-    If no argument is given then under modern mode we select the current CPT.
+**-C**\ [*section*/]\ *master*\|\ *cpt*\|\ *color*\ :math:`_1`,\ *color*\ :math:`_2`\ [,\ *color*\ :math:`_3`\ ,...]\ [**+h**\ [*hinge*]][**+i**\ *dz*][**+u**\|\ **U**\ *unit*][**+s**\ *fname*]
+    Name of a master CPT, an input CPT file or a comma-separated list of colors from which to build a CPT.
+    If no argument is given then under modern mode we select the current CPT, if it is available.
     Generally, the input can be many things:
 
-    #. A standard GMT *master_cpt* file, e.g., *earth* 
+    #. A standard GMT *master* CPT file, e.g., *earth* 
        (see :ref:`Of Colors and Color Legends`) and can be either addressed
-       by *master\_cpt* or *section*/*master_cpt* (without the **.cpt** extension).
-    #. File name of already custom-made *local.cpt* file.
+       by *master* or *section*/*master* (without any **.cpt** extension).
+    #. File name of already custom-made *cpt* file (e.g, *my_colors.cpt*).
     #. Build a linear continuous CPT from *color*\ :math:`_1`,\ *color*\ :math:`_2`\ [,\ *color*\ :math:`_3`\ ,...]
        automatically, where *z* starts at 0 and is incremented by one for each color. In this case,
-       *color*\ :math:`_i` can be a r/g/b (e.g., 255/100/75), or h-s-v triplet (e.g., 180-0.8-1),
-       a c/m/y/k quadruple (e.g., 80/50/40/30), an HTML hexadecimal color (e.g. #aabbcc),
+       *color*\ :math:`_i` can be a *r*/*g*/*b* (e.g., 255/100/75), *h*-*s*-*v* triplet (e.g., 180-0.8-1),
+       a *c*/*m*/*y*/*k* quadruple (e.g., 80/50/40/30), an HTML hexadecimal color (e.g. *#aabbcc*),
        or a :ref:`color name <RGBchart>`. No spaces between commas are allowed.
 
     A few modifiers pertains to hinges and units:
 
     - **+h**: If given a master CPT with soft hinges then you can enable the hinge at
       data value *hinge* [0], whereas for hard-hinge CPTs you can adjust the location
       of the hinge [0] but not disable it.
-    - **+i**: Append increment *dz* to quantize the range [Default uses the exact grid range].
-    - **+s**: Append *fname* to save the finalized cpt in a disk file.
-      This is useful when the cpt was generated automatically, but if used, **must** be
+    - **+i**: Append increment *dz* to quantize the grid range [Default uses the exact grid range].
+    - **+s**: Append *fname* to save the finalized CPT in a disk file.
+      This is useful when the CPT is generated automatically, but if used, **must** be
       at the end of the **-C** option.
-    - **+u**: For any other *master_cpt*, you may convert their *z*-values from 
-      another distance *unit* to meter.
-    - **+U**: Likewise, you may convert their *z*-values from meter to another *unit*.
+    - **+u**: For any other *master* CPT, you may convert their *z*-values from 
+      other distance `Units`_ to meter by appending the original unit code.
+    - **+U**: Likewise, you may convert their *z*-values from meter to other `Units`_
+      by appending the desired unit code.

src/gmt_constants.h

@@ -347,6 +347,9 @@ enum GMT_time_period {
 #define GMT_CPT_EXTENSION	".cpt"
 #define GMT_CPT_EXTENSION_LEN	4U
 
+/* -C (cpt) args for grd*.c plotters: */
+#define CPT_OPT_ARGS "[<section>/]<master>|<cpt>|<*color1,color2[,color3,...][+h[<hinge>]][+i<dz>][+u|U<unit>][+s<fname>]"
+
 #define GMT_IS_ROMAN_LCASE	1	/* For converting Arabic numerals to Roman */
 #define GMT_IS_ROMAN_UCASE	2
 

src/gmt_prototypes.h

@@ -555,6 +555,7 @@ EXTERN_MSC int gmt_cube_BC_set (struct GMT_CTRL *GMT, struct GMT_CUBE *U, unsign
 EXTERN_MSC unsigned int gmt_parse_inv_cpt (struct GMT_CTRL *GMT, char *arg);
 EXTERN_MSC struct GMT_PALETTE * gmt_truncate_cpt (struct GMT_CTRL *GMT, struct GMT_PALETTE *P, double z_low, double z_high);
 EXTERN_MSC void gmt_explain_cpt_output (struct GMTAPI_CTRL *API, char option);
+EXTERN_MSC void gmt_explain_cpt_input (struct GMTAPI_CTRL *API, char option);
 EXTERN_MSC int gmt_prepare_categorical_cpt (struct GMT_CTRL *GMT, char *label, char *key, struct GMT_PALETTE *Pout);
 EXTERN_MSC void gmt_free_int_selection (struct GMT_CTRL *GMT, struct GMT_INT_SELECTION **S);
 EXTERN_MSC struct GMT_INT_SELECTION * gmt_set_int_selection (struct GMT_CTRL *GMT, char *item);

src/gmt_support.c

@@ -54,6 +54,8 @@
  *	gmt_contour_edge_init
  *	gmt_contour_first_pos
  *	gmt_contours
+ *  gmt_explain_cpt_input
+ *  gmt_explain_cpt_output
  *	gmt_cpt_default
  *	gmt_cpt_interval_modifier
  *	gmt_cpt_transparency
@@ -1576,6 +1578,24 @@ void gmt_explain_cpt_output (struct GMTAPI_CTRL *API, char option) {
 		"if it is 7 and label is D then we auto-create weekday name labels.");
 }
 
+void gmt_explain_cpt_input (struct GMTAPI_CTRL *API, char option) {
+	/* Display CPT usage for grd* plotters */
+
+	GMT_Usage (API, 1, "\n-%c%s", option, CPT_OPT_ARGS);
+	GMT_Usage (API, -2, "Color palette file to convert grid values to colors, provided by one of three ways:");
+	GMT_Usage (API, 3, "%s Name one of the master CPTs (no extension) [%s].", GMT_LINE_BULLET, API->GMT->current.setting.cpt);
+	GMT_Usage (API, 3, "%s Name a local regular CPTs (with extension).", GMT_LINE_BULLET);
+	GMT_Usage (API, 3, "%s Specify <color1>,<color2>[,<color3>,...] to build a linear continuous "
+		"CPT to automatically assign continuous colors over the grid data range.", GMT_LINE_BULLET);
+	GMT_Usage (API, -2, "A few modifiers control generation of the active CPT:");
+	GMT_Usage (API, 3, "+h Enable a soft hinge in your master CPT. Append <hinge> to change its value.");
+	GMT_Usage (API, 3, "+i Append <dz> to quantize the grid range [Default uses the exact grid range].");
+	GMT_Usage (API, 3, "+u Scale CPT z-values from another <unit> to meters.");
+	GMT_Usage (API, 3, "+U Scale CPT z-values from meters to another <unit>.");
+	GMT_Usage (API, 3, "+s Append <fname> to save the generated CPT to file.");
+	GMT_Usage (API, -2, "Note: For converting units with +u|U, see units %s.", GMT_LEN_UNITS2_DISPLAY);
+}
+
 int gmt_prepare_categorical_cpt (struct GMT_CTRL *GMT, char *label, char *key, struct GMT_PALETTE *Pout) {
 		bool got_key_file = (key && !gmt_access (GMT, key, R_OK));	/* Want categorical labels read from file */
 		unsigned int ns = 0;

src/grd2kml.c

@@ -144,9 +144,9 @@ static void Free_Ctrl (struct GMT_CTRL *GMT, struct GRD2KML_CTRL *C) {	/* Deallo
 static int usage (struct GMTAPI_CTRL *API, int level) {
 	const char *name = gmt_show_name_and_purpose (API, THIS_MODULE_LIB, THIS_MODULE_CLASSIC_NAME, THIS_MODULE_PURPOSE);
 	if (level == GMT_MODULE_PURPOSE) return (GMT_NOERROR);
-	GMT_Usage (API, 0, "usage: %s %s -N<name> [-Aa|g|s[<altitude>]] [-C<cpt>] [-E<url>] [-F<filter>] "
+	GMT_Usage (API, 0, "usage: %s %s -N<name> [-Aa|g|s[<altitude>]] [-C%s] [-E<url>] [-F<filter>] "
 		"[-H<scale>] [-I[<intensgrid>|<value>|<modifiers>]] [-L<size>] [-S[<extra>]] [-T<title>] [%s] "
-		"[-W<contfile>|<pen>[+s<scl>/<limit>]] [%s] [%s] [%s]\n", name, GMT_INGRID, GMT_V_OPT, GMT_f_OPT, GMT_n_OPT, GMT_PAR_OPT);
+		"[-W<contfile>|<pen>[+s<scl>/<limit>]] [%s] [%s] [%s]\n", name, GMT_INGRID, CPT_OPT_ARGS, GMT_V_OPT, GMT_f_OPT, GMT_n_OPT, GMT_PAR_OPT);
 
 	if (level == GMT_SYNOPSIS) return (GMT_MODULE_SYNOPSIS);
 
@@ -165,12 +165,7 @@ static int usage (struct GMTAPI_CTRL *API, int level) {
 	GMT_Usage (API, 3, "g: Altitude relative to sea surface or ground.");
 	GMT_Usage (API, 3, "s: Altitude relative to sea floor or ground.");
 	GMT_Usage (API, -2, "Optionally, append fixed <altitude> [g0: Clamped to sea surface or ground].");
-	GMT_Usage (API, 1, "\n-C<cpt>");
-	GMT_Usage (API, -2, "Color palette file to convert grid values to colors. Optionally, instead give name of a master cpt "
-		"to automatically assign continuous colors over the data range [%s]; if so, "
-		"optionally append +i<dz> to quantize the range [the exact grid range]. "
-		"Another option is to specify -C<color1>,<color2>[,<color3>,...] to build a "
-		"linear continuous cpt from those colors automatically.", API->GMT->current.setting.cpt);
+	gmt_explain_cpt_input (API, 'C');
 	GMT_Usage (API, 1, "\n-E<url>");
 	GMT_Usage (API, -2, "To store all files remotely, give leading URL [local files only].");
 	GMT_Usage (API, 1, "\n-F<filter>");

src/grdimage.c

@@ -159,10 +159,10 @@ static int usage (struct GMTAPI_CTRL *API, int level) {
 	const char *name = gmt_show_name_and_purpose (API, THIS_MODULE_LIB, THIS_MODULE_CLASSIC_NAME, THIS_MODULE_PURPOSE);
 	const char *extra[2] = {A, " [-A]"};
 	if (level == GMT_MODULE_PURPOSE) return (GMT_NOERROR);
-	GMT_Usage (API, 0, "usage: %s %s %s%s [%s] [-C<cpt>] [-D[r]] [-Ei|<dpi>] "
+	GMT_Usage (API, 0, "usage: %s %s %s%s [%s] [-C%s] [-D[r]] [-Ei|<dpi>] "
 		"[-G<rgb>[+b|f]] [-I[<intensgrid>|<value>|<modifiers>]] %s[-M] [-N] %s%s[-Q[<color>][+z<value>]] "
 		"[%s] [-T[+o[<pen>]][+s]] [%s] [%s] [%s] [%s] %s[%s] [%s] [%s] [%s]%s[%s]\n",
-		name, GMT_INGRID, GMT_J_OPT, extra[API->external], GMT_B_OPT, API->K_OPT, API->O_OPT, API->P_OPT, GMT_Rgeo_OPT, GMT_U_OPT,
+		name, GMT_INGRID, GMT_J_OPT, extra[API->external], GMT_B_OPT, CPT_OPT_ARGS, API->K_OPT, API->O_OPT, API->P_OPT, GMT_Rgeo_OPT, GMT_U_OPT,
 		GMT_V_OPT, GMT_X_OPT, GMT_Y_OPT, API->c_OPT, GMT_f_OPT, GMT_n_OPT, GMT_p_OPT, GMT_t_OPT, GMT_x_OPT, GMT_PAR_OPT);
 
 	if (level == GMT_SYNOPSIS) return (GMT_MODULE_SYNOPSIS);
@@ -186,13 +186,7 @@ static int usage (struct GMTAPI_CTRL *API, int level) {
 			"See GDAL documentation for available drivers. Note: any vector elements are lost.");
 	}
 	GMT_Option (API, "B-");
-	GMT_Usage (API, 1, "\n-C<cpt>");
-	GMT_Usage (API, -2, "Color palette file to convert grid values to colors. Optionally, name a master cpt "
-		"to automatically assign continuous colors over the data range [%s]; if so, "
-		"optionally append +i<dz> to quantize the range [the exact grid range]. "
-		"Another option is to specify -C<color1>,<color2>[,<color3>,...] to build a "
-		"linear continuous cpt from those colors automatically. Append +s<fname> to save the generated cpt ",
-		"in a disk file.", API->GMT->current.setting.cpt);
+	gmt_explain_cpt_input (API, 'C');
 	GMT_Usage (API, 1, "\n-D[r]");
 	if (API->external)	/* External interface */
 		GMT_Usage (API, -2, "Input is an image instead of a grid. Append r to equate image region to -R region.");

src/grdvector.c

@@ -115,9 +115,9 @@ static void Free_Ctrl (struct GMT_CTRL *GMT, struct GRDVECTOR_CTRL *C) {	/* Deal
 static int usage (struct GMTAPI_CTRL *API, int level) {
 	const char *name = gmt_show_name_and_purpose (API, THIS_MODULE_LIB, THIS_MODULE_CLASSIC_NAME, THIS_MODULE_PURPOSE);
 	if (level == GMT_MODULE_PURPOSE) return (GMT_NOERROR);
-	GMT_Usage (API, 0, "usage: %s <gridx> <gridy> %s [-A] [%s] [-C[<cpt>]] [-G<fill>] [-I[x]<dx>/<dy>] "
+	GMT_Usage (API, 0, "usage: %s <gridx> <gridy> %s [-A] [%s] [-C%s] [-G<fill>] [-I[x]<dx>[/<dy>]] "
 		"%s[-N] %s%s[-Q<params>] [%s] [-S[i|l]<length>|<scale>[+c[<slon>/]<slat>][+s<refsize>]] [-T] [%s] [%s] [-W<pen>] [%s] [%s] [-Z] "
-		"%s [%s] [%s] [%s] [%s] [%s]\n", name, GMT_J_OPT, GMT_B_OPT, API->K_OPT, API->O_OPT, API->P_OPT,
+		"%s [%s] [%s] [%s] [%s] [%s]\n", name, GMT_J_OPT, GMT_B_OPT, CPT_OPT_ARGS, API->K_OPT, API->O_OPT, API->P_OPT,
 		GMT_Rgeo_OPT, GMT_U_OPT, GMT_V_OPT, GMT_X_OPT, GMT_Y_OPT, API->c_OPT, GMT_f_OPT, GMT_l_OPT, GMT_p_OPT, GMT_t_OPT, GMT_PAR_OPT);
 
 	if (level == GMT_SYNOPSIS) return (GMT_MODULE_SYNOPSIS);
@@ -128,15 +128,10 @@ static int usage (struct GMTAPI_CTRL *API, int level) {
 	GMT_Message (API, GMT_TIME_NONE, "\n  OPTIONAL ARGUMENTS:\n");
 	GMT_Usage (API, 1, "\n-A Grids have polar (r, theta) components [Default is Cartesian (x, y) components].");
 	GMT_Option (API, "B-");
-	GMT_Usage (API, 1, "\n-C[<cpt>]");
-	GMT_Usage (API, -2, "Color palette file to convert vector length to colors. Optionally, name a master cpt "
-		"to automatically assign continuous colors over the data range [%s]; if so, "
-		"optionally append +i<dz> to quantize the range [the exact grid range]. "
-		"Another option is to specify -Ccolor1,color2[,color3,...] to build a linear "
-		"continuous cpt from those colors automatically.", API->GMT->current.setting.cpt);
+	gmt_explain_cpt_input (API, 'C');
 	gmt_fill_syntax (API->GMT, 'G', NULL, "Select vector fill [Default is outlines only].");
-	GMT_Usage (API, 1, "\n-I[x]<dx>/<dy>");
-	GMT_Usage (API, -2, "Plot only those nodes that are <dx>/<dy> apart [Default is all nodes]. "
+	GMT_Usage (API, 1, "\n-I[x]<dx>[/<dy>]");
+	GMT_Usage (API, -2, "Plot only those nodes that are <dx> and <dy> apart [Default is all nodes]. "
 		"Optionally, use -Ix<fact>[/<yfact>] to give multiples of grid spacing.");
 	GMT_Option (API, "K");
 	GMT_Usage (API, 1, "\n-N Do Not clip vectors that exceed the map boundaries [Default will clip].");

src/grdview.c

@@ -421,10 +421,10 @@ static int usage (struct GMTAPI_CTRL *API, int level) {
 
 	const char *name = gmt_show_name_and_purpose (API, THIS_MODULE_LIB, THIS_MODULE_CLASSIC_NAME, THIS_MODULE_PURPOSE);
 	if (level == GMT_MODULE_PURPOSE) return (GMT_NOERROR);
-	GMT_Usage (API, 0, "usage: %s <topogrid> %s [%s] [-C[<cpt>]] [-G<drapegrid> | <image> | -G<grd_r> -G<grd_g> -G<grd_b>] "
+	GMT_Usage (API, 0, "usage: %s <topogrid> %s [%s] [-C%s] [-G<drapegrid> | <image> | -G<grd_r> -G<grd_g> -G<grd_b>] "
 		"[-I[<intensgrid>|<value>|<modifiers>]] [%s] %s[-N[<level>][+g<fill>]] %s%s[-Q<args>[+m]] [%s] [-S<smooth>] "
 		"[-T[+o[<pen>]][+s]] [%s] [%s] [-W<type><pen>] [%s] [%s] %s[%s] [%s] [%s] [%s] [%s]\n",
-		name, GMT_J_OPT, GMT_B_OPT, GMT_Jz_OPT, API->K_OPT, API->O_OPT, API->P_OPT, GMT_Rgeoz_OPT, GMT_U_OPT, GMT_V_OPT,
+		name, GMT_J_OPT, GMT_B_OPT, CPT_OPT_ARGS, GMT_Jz_OPT, API->K_OPT, API->O_OPT, API->P_OPT, GMT_Rgeoz_OPT, GMT_U_OPT, GMT_V_OPT,
 		GMT_X_OPT, GMT_Y_OPT, API->c_OPT, GMT_f_OPT, GMT_n_OPT, GMT_p_OPT, GMT_t_OPT, GMT_PAR_OPT);
 
 	if (level == GMT_SYNOPSIS) return (GMT_MODULE_SYNOPSIS);
@@ -434,13 +434,7 @@ static int usage (struct GMTAPI_CTRL *API, int level) {
 	GMT_Option (API, "J-Z");
 	GMT_Message (API, GMT_TIME_NONE, "\n  OPTIONAL ARGUMENTS:\n");
 	GMT_Option (API, "B-");
-	GMT_Usage (API, 1, "\n-C[<cpt>]");
-	GMT_Usage (API, -2, "Color palette file to convert grid values to colors. Optionally, name a master cpt "
-		"to automatically assign continuous colors over the data range [%s]; if so, "
-		"optionally append +i<dz> to quantize the range [the exact grid range]. "
-		"Another option is to specify -C<color1>,<color2>[,<color3>,...] to build a "
-		"linear continuous cpt from those colors automatically. Append +s<fname> to save the generated cpt ",
-		"in a disk file.", API->GMT->current.setting.cpt);
+	gmt_explain_cpt_input (API, 'C');
 	GMT_Usage (API, 1, "\n-G<drapegrid> | <image> | -G<grd_r> -G<grd_g> -G<grd_b>");
 	GMT_Usage (API, -2, "Specify how to color the 3-D surface defined by <topogrid>:");
 	GMT_Usage (API, 3, "%s Provide a grid (<drapegrid>) and colors will be determined from it and the cpt.", GMT_LINE_BULLET);