Hello, thanks to contributors of this list I was able to use ppchtex with LaTeX when I encountered a "\writestatus: Undefined control sequence" problem: http://www.ntg.nl/pipermail/ntg-context/2009/044672.html Everything went well (though I have a little use of ppchtex) but, as I tried it some days ago, I was facing another trouble pointed out by the following MCE: \listfiles{} \documentclass{article} \usepackage{etex,m-pictex,m-ch-en} \begin{document} \startchemical \chemical{2H_2,PLUS,O_2,GIVES,2H_2O} \stopchemical \end{document} The error is: ! Undefined control sequence. \dodogetgroupargument ->\normalifx \nextargument \bgroup \endrobusttest \nos... l.6 \chemical{ 2H_2,PLUS,O_2,GIVES,2H_2O} ? Here is my files list: *File List* article.cls 2007/10/19 v1.4h Standard LaTeX document class size10.clo 2007/10/19 v1.4h Standard LaTeX file (size option) etex.sty 1998/03/26 v2.0 eTeX basic definition package (PEB) m-pictex.sty 2004/07/30 package wrapper for m-pictex.tex m-pictex.tex m-ch-en.sty 2004/07/30 package wrapper for m-ch-en.tex m-ch-en.tex It seems that mkiv seems still not ok with my up-to-date TeX Live 2009, as: $ more test-context-minimal.tex \starttext Hello World! \stoptext $ context test-context-minimal.tex MTXrun | unknown script 'context.lua' or 'mtx-context.lua' But mkii is ok (tested with `texexec test-context-minimal.tex`). And, with mkii, the following ppchtex MCE is OK: \usemodule[pictex,chemic] \starttext \startchemical \chemical[SIX,B,R,RZ][1,2,3,4,5,6] \stopchemical \stoptext Thanks in advance for any hint... -- Denis