The documentation is kind of lacking.
Could anyone explain the meaning of blue solid/dotted lines and red solid lines between words here? How are they different from the dotted versions?

enter image description here

Looking into the source code, I see this but I don't understand the color code and the code itself.

enter image description here

Source: https://tug.ctan.org/macros/luatex/generic/lua-visual-debug/doc/lvdebug-doc.pdf

  • When I click your link and look in that pdf file, the parts you marked in yellow look dotted as well (a bit cramped, but dotted). Like this.
    – mickep
    Commented Jan 2, 2023 at 7:57
  • The one are spaces that have been stretched a bit, the other have been shrinked. Commented Jan 2, 2023 at 8:18
  • @mickep The image above is the result that I copied the code and compiled myself as plain TeX on Overleaf. It looks different from the image in the documentation.
    – hana
    Commented Jan 2, 2023 at 8:18
  • Colour coding is RG: red-green-blue RGB model; G = grayscale. values [0-1]. PDF literal commands. Lowercase version rg and g should range [0-255].
    – Cicada
    Commented Jan 2, 2023 at 8:22
  • PDF32000_2008 may help if you want to delve into the PDF standard, and what all the PDF literals are. Correction: RG = stroking colour; rg = nonstroking colour (=fill).
    – Cicada
    Commented Jan 2, 2023 at 8:41

1 Answer 1


The difference in appearance of the dotted / solid lines are a result of a programming error.

Next version (0.9) will update the documentation and fix the error.

(PDF operator S should be used for a dash pattern and not s)

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