\ifcase\tg@case\relax
  \def\tg@pdfcreator@app{pdflatex}
%   <customizations-for-pdflatex>
\or
  \def\tg@pdfcreator@app{lualatex}
%   <customizations-for-lualatex>
\or
  \def\tg@pdfcreator@app{xelatex}
%   <customizations-for-xelatex>
\or
  \def\tg@pdfcreator@app{ps2pdf}
%   <customizations-for-ps2pdf>
\or
  \def\tg@pdfcreator@app{acrodist}
%   <customizations-for-acrodist>
\fi
