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Hi,
Like all TeX related things you can find it in CTAN, exactly in
well, not *all* TeX relatet stuff is on CTAN...
http://www.ctan.org/tex-archive/macros/latex209/contrib/misc/ebnf.sty
The file is old (1991)
and incorrect (the last Cat is missing its backslash). And even with this backslash, the formatting is strange. I'd suggest something like this (warning: ugly(!!) LaTeX code ahead): \begingroup \catcode`\|=13 \catcode`\<=13 \gdef\EBNF {\list{???}% {% \def|{$\mid$}% \def\makelabel##1{<##1> ::=}% \def\Cat##1{$\langle${\it ##1\/}$\rangle$} \def<##1>{\Cat{##1}} \parsep=0pt \itemsep=\smallskipamount \leftmargin=\parindent \advance\leftmargin+2em \labelsep=0.5em \labelwidth=1.5em \raggedright \catcode`\|=13 \catcode`\<=13 }% } \endgroup \let\endEBNF\endlist \documentclass{article} \usepackage{calc} \begin{document} \begin{EBNF} \item[glue] <dimen> [~`plus' <stretch>~] [~`minus' <stretch>~]. \item[stretch] <dimen> | <fil dimen>. \item[fil dimen] <factor> (~`fil' | `fill' | `filll'~). \end{EBNF} \end{document} which looks like this: <glue>::= <dimen> [ ‘plus’ <stretch> ] [ ‘minus’ <stretch> ]. <stretch>::= <dimen>| <fil dimen>. <fil dimen>::= <factor >( ‘fil’ | ‘fill’ | ‘filll’ ). Patrick -- mon trainsistor j'adore