Oddments
LaTeX 2.09 :
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  \documentstyle[twoside,epsfig]{article}  % Select style.
  \begin{document}                         % Begin document.
    .
    .                                      % Text of document.
    .
  \end{document}                           % End document.
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| 
  \documentclass[twoside]{article}      % Select style.
  \usepackage{epsfig}
  \begin{document}                      % Begin document.
    .
    .                                   % Text of document.
    .
  \end{document}                        % End document.
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Use SliTeX.
Or LaTeX Beamer. . .
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\font\stdtenrm=cmr10 scaled\magstep0
\font\bigtenrm=cmr10 scaled\magstep1
\font\BIGtenrm=cmr10 scaled\magstep2
{\stdtenrm This is {\tt cmr10} scaled at normal size.}
\smallskip
{\bigtenrm This is {\tt cmr10} scaled once by 1.2.}
\smallskip
{\BIGtenrm This is {\tt cmr10} scaled twice by 1.2.}
\bye
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\font\stdtenrm=cmr10 
\font\fivetenrm=cmr5 scaled 2000
\font\stdtentt=cmtt10 
\font\fivetentt=cmtt5 scaled 2000
\font\bigbold=cmbx14
\centerline{{\bigbold Font Design Size}}
\bigskip
{\stdtenrm This is {\stdtentt cmr10} scaled at normal size.}
\smallskip
{\fivetenrm This is {\fivetentt cmr5} scaled to twice its normal size.}
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\font\courier    = pcrr8a
\font\titlefont  = pagd8a
\font\pstenrm    = ptmb8a
\font\stdtenrm   = cmr10
{\titlefont Using Postscript Fonts}
\bigskip
{\stdtenrm This is {\tt cmr10}, \TeX's ``standard'' Computer Modern font.}
\smallskip
{\pstenrm This is {\courier Times}, one of Postscript's standard fonts.}
\bye
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Used for designing and building fonts. For more information have a look at its home web site.
export TEXFONTS=/usr/share/texmf/fonts//:/var/cache/fonts//:/home/user/texmf/fonts//
In (Plain) TeX use \def whilst in LaTeX use \newcommand. . .