4.3 LaTeX cfg file

Is in the LaTeX input path (in particular in the current directory) a file called tbook.cfg, it is included immediately before \begin{document}. Typically you will redefine here the macro \MakeTitlePage, but you can also change the document font for example:

     \ifpdflatex\else\ifgallery\else
       \psfonts
     \makeatletter
     
     \RequirePackage{geometry}
     \@ifpackagelater{geometry}{2002/07/08}{%
       \def\opt{includehead,}}{\def\opt{}}
     \expandafter\geometry\expandafter{\opt
                     nofoot,a4paper,
                     lmargin=2.7cm,rmargin=3cm,     % left and right margin
                     tmargin=1.8cm,bmargin=3.9cm,   % top and bottom margin
                     headheight=0.5cm,
                     headsep=0.5cm,twosideshift=0cm}
     \makeatother
     \fi\fi

The first three lines activate Times font, the rest sets the page margins (for odd pages). Both is only done if we are not producing a PDF (\ifpdflatex\else) and if we are nor producing a so-called gallery (\ifgallery\else). Adjust the values for your needs. You can also use another unit, like “in”.

With such a cfg file you can do very similar things as with a LaTeX sty file, see LaTeX sty file. But the cfg file mechanism is included in tbook to do simple things in a quick and simple way.