with the plain tex \hsize 10pt \hfuzz20pt a supercalifragilisticexpialidocious \bye
with pdftex I get no warnings and a multi-line output with several hyphens. with 0.87 built for example just by luatex --ini plain.tex \\dump I get no hyphenation and it comes on one line with: Overfull \hbox (130.22255pt too wide) in paragraph at lines 4--5 \tenrm supercalifragilisticexpialidocious | Am I missing some setup needed to enable hyphenation? David
