Hi, on line 800 you pick the wrong number of arguments. \unexpanded\def\doifelseemptyvariable#1#2%  %{\edef\m_syst_string_one{\csname\??variables\ifcsname\??variables#1:#2\endcsname#1:#2\else:\fi\endcsname}%   {\edef\m_syst_string_one{\begincsname\??variables#1:#2\endcsname}%    \ifx\m_syst_string_one\empty -    \expandafter\firstoffourarguments +    \expandafter\firstoftwoarguments    \else      \expandafter\secondoftwoarguments    \fi} Wolfgang