# Show the hyphenation points

This LaTeX example adds a function to the post_linebreak_filter callback. The function iterates through all the nodes in the paragraph (and descends into the vlist and hlist nodes) and inserts a small rule where the discretionary nodes are.

\documentclass[12pt,a4paper]{scrartcl}
\usepackage[english]{babel}
\usepackage{blindtext}
\usepackage{fontspec}
\directlua{
if head.id == 0 or head.id == 1 then % hlist, vlist
elseif head.id == 7 then             % disc
local n = node.new("whatsit","pdf_literal")
n.mode = 0
n.data = "q 0.3 w 0 2 m 0 7 l S Q"
end
end
return true
end