Output Formats

The format follows the output name, in the library (fig%save(file)) and in scripts (set output):

Output	Format
*.html, *.htm	interactive page: SVG plus the embedded viewer
*.svg	static SVG
*.txt	text, the gnuplot dumb or block terminal
-	text on the standard output

In scripts, set terminal svg|html|dumb|block changes the format of the default output (the one derived from the script name) but never an output set explicitly with set output.

SVG

A standalone SVG document, 600 x 480 px by default (set terminal svg size W,H), font Arial/Helvetica 12 px.

• The data of each panel live in a nested <svg class="fs-plot"> whose viewBox is the unit square: coordinates are written with 6 decimals of the plot area, and vector-effect="non-scaling-stroke" keeps line widths in pixels.
• Panels are <g class="fs-axes"> groups carrying their geometry and axis ranges as data-* attributes; the grid and the ticks are the groups fs-grid, fs-xticks, fs-yticks, error bar caps an fs-caps overlay. The viewer regenerates these; for a static SVG they are ordinary drawing. A polar panel adds its grid as fs-pgrid in the plot area (zoomed with the data) and its r tick labels and theta labels as fs-polar, hidden while zoomed. Arrow shafts are fs-vectors paths, their heads and the text of labels the pixel overlays fs-heads and fs-labels (each text carrying its data anchor), redrawn by the viewer after a zoom.
• Each series is a group fs-series and its key entry a group fs-key-entry, both numbered by data-series (from 1, in plot order): the viewer hides a series when its entry is clicked.
• All numbers are formatted by integer arithmetic, identically on every compiler: the same figure gives the same bytes.

HTML

The SVG document inline in a minimal page, followed by the viewer script. The page loads nothing from the network. set terminal html refresh S (or fig%set_refresh(S)) makes it reload itself every S seconds; watch mode sets it automatically.

Text

The layout engine draws on a grid of character cells, 79 x 24 by default (set terminal dumb size COLS,ROWS):

• series with gnuplot's symbols *, #, $, %, @, &, =, +, one per color in order of use;
• the frame with +, -, |, the grid with ., superscripts as ^ (10^-5);
• error bars as | or - runs, without caps.

With ansi, ansi256 or ansirgb (set terminal dumb ansi, as gnuplot) each series is drawn in its color through ANSI escape sequences: the nearest of the six basic terminal colors, of the 256-color palette, or the color itself. The frame, the text, and black or white series keep the terminal's own color, readable on a dark or a light background.

                             dumb
  1.3+--------+--------+-------+--------+--------+--------+
     |                                           cd****** |
     |                                           |    |   |
  1.2+                                  |    |   |    |   +
     |                         |    |   |    |   |    |   |
  1.1+   #*   |   |    |   |   |    |   |    |   |    |   +
     |   | ***#   |    |   |   |    |   |    |   |    |   |
     |        |***#****#***#***#****#***#****#***#****#***|
    1+            |    |   |   |    |   |    |   |    |   +

Block characters

set terminal block (gnuplot 5.4+) draws the same layout with Unicode characters made of dots, for curves smoother than the symbols of dumb: half (1 x 2 dots per character), quadrants (2 x 2, the default), sextants (2 x 3, Unicode 13 fonts) or braille (2 x 4). The text — tick labels, titles, the key — is written over the graphics.

$ foresight cb_block.gp

  0.6⡏⠉⠉⠉⠉⠉⠉⠉⠉⠙⠉⠉⠉⠉⠉⠉⠉⠉⠉⠋⠉⠉⠉⠉⠉⠉⠉⠉⠙⠉⠉⠉⠉⠉⠉⠉⠉⠉⠋⠉⠉⠉⠉⠉⠉⠉⠉⠙cd⢉⣉⣉⣉⣉⣉⠉⡇
     ⣇                                                        ⡇
     ⡏⢆                                                       ⡇
  0.5⡏⠙⡄                                                     ⠈⡇
     ⡇ ⢣                                                      ⡇
     ⡇ ⠈⡆                                                     ⡇
  0.4⡏⠁ ⢱                                                    ⠈⡇
     ⡇  ⠈⡆          ⢀⠔⠒⠒⢄⡀                                    ⡇
  0.3⣇⡀  ⢸         ⡔⠁    ⠈⠢⣀        ⢀⣀⡠⠤⠤⠤⠤⣀⣀⣀        ⢀⣀⣀⣀⣀⣀⣀⣀⡇
     ⡇    ⢇      ⢀⠜         ⠑⠢⠤⣀⡠⠤⠒⠊⠁         ⠉⠉⠉⠉⠉⠉⠉⠉⠁       ⡇
     ⡇    ⠘⡄    ⢀⠎                                            ⡇
  0.2⣇⡀    ⠘⡄  ⡠⠊                                            ⢀⡇
     ⡇      ⠘⠢⠒⠁                                              ⡇
     ⡇                                                        ⡇
  0.1⣇⣀⣀⣀⣀⣀⣀⣀⣀⣠⣀⣀⣀⣀⣀⣀⣀⣀⣀⣄⣀⣀⣀⣀⣀⣀⣀⣀⣠⣀⣀⣀⣀⣀⣀⣀⣀⣀⣄⣀⣀⣀⣀⣀⣀⣀⣀⣠⣀⣀⣀⣀⣀⣀⣀⣀⣀⡇
     0       20        40       60        80       100       120

The colors are those of dumb (set terminal block braille ansirgb); without them, the series are told apart by the key only, as in gnuplot. A character holds one color, the last series drawn in it. Unlike gnuplot, a character without dots is a blank (gnuplot writes the empty Braille pattern), so the lines copy and trim as text; points are a dot and its four neighbours, clipped to the plot area.

Images

with image writes an embedded PNG (8-bit RGBA, uncompressed: a few bytes per pixel, identical bytes for identical data) with image-rendering: pixelated, so a pixel stays a sharp square at any zoom. In text, a character per cell.

Themes

set terminal ... theme vfd (or lcd, classic) recolors any output as a 1980s digital dashboard: see Themes and segmented fills. SVG and HTML take the page, frame, grid and series colors and, for vfd, a glow; text takes the series colors only.

Atomic writes

Every file output is written to <file>.tmp and renamed over <file> when complete (POSIX rename), so a browser, an editor or a copy never sees a partial file.