Hello again Patrick, The reason I've taken so long to reply, is that I've been trying to understand TeX's line-breaking mechanism. Your perceptive question:
Why is there a difference between knuth.tex and tufte.tex in the example (try \input tufte instead of \input knuth).
In the example below %-- tryISOLayout.ctx ---------------------------------------- %output=pdf \setuppapersize[A4][A4] \setupencoding[default=texnansi] \setupbodyfont[cmr,14.4pt] \def\GoldenRatio{1.61803} \setbox0\hbox{\dorecurse{26}{\character\recurselevel}} \setuplayout[width=2.5\wd0, header=\lineheight, footer=\lineheight, height=\GoldenRatio\makeupwidth, headerdistance=\dimexpr( (\makeupheight-37\lineheight-\headerheight-\footerheight) /2), footerdistance=\headerdistance, backspace=\dimexpr(\makeupwidth/7), topspace=\dimexpr(\makeupwidth/7)] \showframe \starttext \startlinenumbering \dorecurse{5}{\input tufte} \stoplinenumbering \stoptext %-- end tryISOLayout.ctx ------------------------------------ I think is due to TeX trying very hard not to generate a widow line. Even after fiddling around with \looseness, I couldn't force TeX to add the 37th line. I've a feeling that if you come across a pathological case like the above, you really have to follow Knuth's advice and rewrite the paragraph.