\input basic
\tracingonline1\tracingcommands2\tracingstats2
  \tracingpages1\tracingoutput1\tracinglostchars1
  \tracingmacros2\tracingparagraphs1\tracingrestores1
  \showboxbreadth9999\showboxdepth9999\errorstopmode
\def\~#1{{\accent"7E #1}}
\xchar550\hbox to10pt{\xchar`A\~x\~X\~{\xchar'570}\~{\xchar'1130}}
\tolerance=10000\discretionary{\xchar`a}{\xchar`b}{\xchar`c}\showlists
$$\hbox{\xchar0}$$

\end