In inline math, \to works fine (produces a right arrow), but in a figure caption all hell breaks loose. The culprit may be this redefinition of \to in enco-ini.tex: $ find texmf -name '*.tex' |xargs egrep -n '\\((e|g|)def|let)\\to\b' texmf/tex/context/base/core-pos.tex:642: %\edef\to {\POSprefix#1}% texmf/tex/context/base/enco-ini.tex:1565: {\appendtoks\let\to\everylowercase texmf/tex/context/base/enco-ini.tex:1570: {\appendtoks\let\to\everyuppercase [context : ver: 2006.04.17 23:14] This test file: \starttext \placefigure[abc]{ABC $n\to1$.}{} \input tufte \stoptext produces lots of errors beginning with ERROR: Missing control sequence inserted. --- TeX said --- <inserted text> \inaccessible <to be read again> 1 \convertargument #1\to #2->\dodoglobal \edef #2 {\detokenize {#1}} <argument> ABC $n\to 1 $. \docompletefloat ... \doglobal \convertargument #6 \to \asciititle \ifnofloat... <argument> ...abc}{figure}{ABC $n\to 1$.}\nextbox \else \docompletefloat {fi... ... l.2 \placefigure[abc]{ABC $n\to1$.}{} \input tufte