# gnuplot 6.0 gallery: licence and coverage review

Reviewed 11 October 2026 against the [official 6.0 gallery](https://gnuplot.sourceforge.net/demo_6.0/).
The available gallery identifies its renderer as gnuplot 6.0.5. The tour was
compared with its plot-family catalogue, rather than importing its demo bundle.

## Upstream licence

The [gnuplot 6.0 manual, Copyright section](https://www.gnuplot.info/docs_6.0/Gnuplot_6.pdf)
states the project's own **gnuplot licence**. Reuse and redistribution require
retaining copyright and permission notices. Modified source distribution has
additional conditions, including distributing modifications as patches; modified
binaries have identification and source-change requirements. It is not a CC0
licence. The [official FAQ](https://www.gnuplot.info/faq/index.html) also notes
that some files have their own additional licence terms.

The gallery index does not supply a separate blanket licence for all scripts,
data or pictures. Check the exact source-file notices before copying one.
For example, the [multiplot demo](https://gnuplot.sourceforge.net/demo_4.6/multiplt.html)
explicitly declares a public-domain release. That is a file-specific declaration,
not permission to treat the whole gallery as public domain.

The complete candlesticks and parallel-axis scripts were also inspected through
the [unofficial upstream Git mirror](https://github.com/gnuplot/gnuplot):
[candlesticks.dem](https://github.com/gnuplot/gnuplot/blob/master/demo/candlesticks.dem)
and [parallel.dem](https://github.com/gnuplot/gnuplot/blob/master/demo/parallel.dem).
Neither contained an explicit alternative licence declaration. Some other full
source-file requests were unavailable; displayed gallery excerpts are not a
substitute for checking those files' complete notices. This review does not
claim that every demo or dataset has identical terms.

## What this tour adds

These 30 examples are independent implementations with original synthetic data,
prose and scripts. No upstream demo scripts, datasets or rendered images are
included. gnuplot syntax and plotting methods are used to teach the features.
The tour's original content remains CC0, and its original arrangement and
publisher structure remain CC BY 4.0, as described in [LICENSE.md](../LICENSE.md).
The gnuplot executable is an external dependency and is not redistributed here.

| Gap in the earlier tour | New sequence | Gallery reference |
| --- | --- | --- |
| Nonlinear least-squares fitting and residuals | PLT-15-011–015 | [fit](https://gnuplot.sourceforge.net/demo_6.0/fit.html) |
| Cubic and shape-preserving interpolation | PLT-15-016–020 | [monotonic splines](https://gnuplot.sourceforge.net/demo_6.0/monotonic_spline.html) |
| OHLC candlesticks with computed extrema | PLT-21-009–013 | [candlesticks](https://gnuplot.sourceforge.net/demo_6.0/candlesticks.html) |
| Overlapping measurements and bee swarms | PLT-21-014–018 | [jitter](https://gnuplot.sourceforge.net/demo_6.0/jitter.html) |
| Multivariate parallel-axis plots | PLT-22-007–011 | [parallel axes](https://gnuplot.sourceforge.net/demo_6.0/parallel.html) |
| Calendar schedules and progress | PLT-28-008–012 | [Gantt](https://gnuplot.sourceforge.net/demo_6.0/gantt.html) |

Each sequence begins with a baseline and changes one concept at a time.
Fixtures repeat in every complete downloadable script. All 323 previous
examples and their IDs are retained; the total is now 353 in 29 chapters.

## Coverage and further candidates

The existing tour already covers ordinary functions and data input, axes and
scales, lines and fills, error bars and boxplots, histogram families, statistics
and automatic min/max detection, grouping brackets, scatter/PCA, heatmaps,
contours and surfaces, radar plots, sectors, waterfalls and output formats.

Useful advanced candidates remain: vector fields, circle glyphs, horizontal
steps, convex/concave hulls, density/violin plots, wind roses, broken/nonlinear
axes, 3D lighting and filled contours. Volume data, animation, watchpoints and
special functions would need distinct data or interaction workflows. These
were not added in this pass; the comparison is a coverage review, not a claim
that the tour reproduces every demonstration in the gallery.