--------------------X PIXMAP (.xpm) IMAGE FORMAT, VERSION 3---------------------
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An X PixMap image is stored as a fragment of C source code in which the first
line is "/* XPM */" and the remaining lines define an array of ``static char*''
(usually with a name identical to that of the file with '_' in place of '.').
This array contains the following strings, in order:
 - a string containing four or six decimal integers, separated by whitespace,
   which, in order, specify the width of the image in pixels (hereafter called
   $width), the height of the image in pixels (hereafter called $height), the
   number of colors used in the image (hereafter called $colors), the number of
   characters used to represent each color (hereafter called $cpp), and,
   optionally, the x- and y-coordinates of the image's "hotspot" (for using the
   image as a mouse cursor).  The string may also optionally end with the
   substring "XPMEXT" (separated from preceding integers by whitespace), which
   indicates that the image uses extensions.
 - "$colors" strings, specifying the colors used in the image.  Each string
   consists of the following items separated by whitespace:
  - "$cpp" characters (immediately at the beginning of the string) which will
    be used to represent a pixel in the image data
  - one or more pairs of keys & color values describing what color(s) to use
    for the associated pixel(s)
  - A key is one of:
   - "c" - indicates that the corresponding color should be used when the image
     is displayed in a color visual
   - "m" - indicates that the corresponding color should be used when the image
     is displayed in a monochrome visual
   - "g4" - indicates that the corresponding color should be used when the
     image is displayed in a 4-color/4-level greyscale visual
   - "g" - indicates that the corresponding color should be used when the image
     is displayed in a greyscale visual with more than four colors/levels
   - "s" - indicates that the corresponding color is a symbolic name describing
     a color that can be overridden at load time (e.g., "light_color",
     "lines_in_mix", "lines_in_dark", "dark_color", etc.)
  - A color value is one of:
   - a color name (corresponding to an entry in an X11 color names file)
   - a '#' followed by a hexadecimal RGB code
   - a '%' followed by an HSV code
   - the string "None", indicating a transparent or otherwise omitted pixel
  - Keys are separated from color values by whitespace.
 - "$height" strings (corresponding to the rows of the image from top to
   bottom) of length "$width * $cpp" in which each consecutive substring of
   length "$cpp" describes a pixel of the image (from left to right) as having
   the color(s) defined for that substring by the preceding section
 - If & only if the "XPMEXT" flag is present:
  - one or more extension subsections, which take two possible forms:
   - a string containing, in order, "XPMEXT", whitespace, the name of the
     extension, whitespace, and the extension data
   - a string containing, in order, "XPMEXT", whitespace, and the name of the
     extension, followed by one or more strings of extension data
  - the string "XPMENDEXT"