\documentclass{article}
\usepackage[LGR,OT1,TS1,T1]{fontenc} % load the desired encodings
\usepackage{fonttable}
\usepackage{hyperref}
\usepackage[utf8]{inputenc}
\usepackage[greek,english]{babel}
\usepackage{gfsdidot}
%To load the macros doing some test or displaying standard texts.
\usepackage{testDidot}

\setlength{\parindent}{0pt}
\setlength{\parskip}{1ex plus 1ex minus .5ex}

\newcommand\mainFont{udidot}
\newcommand\greekFont{udidot}

%This command prints a normalized example of text.
%
%The macro has 3 arguments:
%       1) The encoding
%       2) The series
%       3) The shape
\newcommand\textSample[3]{%
  \begingroup
     \fontencoding{#1}\fontfamily{\mainFont}%
     \fontseries{#2}\fontshape{#3}%
     \selectfont
     \TexStdTestText\par
     \names
     \frenchCarSample
  \endgroup
}

%This command prints a normalized example of text in greek.
%
%The macro has 2 arguments:
%       2) The series
%       3) The shape
\newcommand\textSampleGreek[2]{%
  \begingroup
     \fontencoding{LGR}\fontfamily{\greekFont}%
     \fontseries{#1}\fontshape{#2}%
     \selectfont
     \oldgreekSample
     \modernGreekSample
  \endgroup
}

\begin{document}

\tableofcontents

\newpage

\section{GFS Didot, OT1}
\subsection{Series: m, shape n}
\xfonttable{OT1}{\mainFont}{m}{n}
\textSample{OT1}{m}{n}

\subsection{Series: m, shape it}
\xfonttable{OT1}{\mainFont}{m}{it}
\textSample{OT1}{m}{it}

\subsection{Series: b, shape n}
\xfonttable{OT1}{\mainFont}{b}{n}
\textSample{OT1}{b}{n}

\subsection{Series: b, shape it}
\xfonttable{OT1}{\mainFont}{b}{it}
\textSample{OT1}{b}{it}

\subsection{Series: m, shape sl}
\xfonttable{OT1}{\mainFont}{m}{sl}
\textSample{OT1}{m}{sl}

\subsection{Series: b, shape sl}
\xfonttable{OT1}{\mainFont}{b}{sl}
\textSample{OT1}{b}{sl}

\subsection{Series: m, shape sc}
\xfonttable{OT1}{\mainFont}{m}{sc}
\textSample{OT1}{m}{sc}

\subsection{Series: b, shape sc}
\xfonttable{OT1}{\mainFont}{b}{sc}
\textSample{OT1}{b}{sc}

\subsection{Series: m, shape sco}
\xfonttable{OT1}{\mainFont}{m}{sco}
\textSample{OT1}{m}{sco}

\subsection{Series: m, shape ui}
\xfonttable{OT1}{\mainFont}{m}{ui}
\textSample{OT1}{m}{ui}

\section{GFS Didot, TS1}
\subsection{Series: m, shape n}
\xfonttable{TS1}{\mainFont}{m}{n}

\subsection{Series: m, shape it}
\xfonttable{TS1}{\mainFont}{m}{it}

\subsection{Series: b, shape n}
\xfonttable{TS1}{\mainFont}{b}{n}

\subsection{Series: b, shape it}
\xfonttable{TS1}{\mainFont}{b}{it}

\subsection{Series: m, shape ui}
\xfonttable{TS1}{\mainFont}{m}{ui}

\subsection{Series: m, shape sl}
\xfonttable{TS1}{\mainFont}{m}{sl}

\subsection{Series: b, shape sl}
\xfonttable{TS1}{\mainFont}{b}{sl}

\section{GFS Didot, T1}
\subsection{Series: m, shape n}
\xfonttable{T1}{\mainFont}{m}{n}
\textSample{T1}{m}{n}

\subsection{Series: m, shape it}
\xfonttable{T1}{\mainFont}{m}{it}
\textSample{T1}{m}{it}

\subsection{Series: b, shape n}
\xfonttable{T1}{\mainFont}{b}{n}
\textSample{T1}{b}{n}

\subsection{Series: b, shape it}
\xfonttable{T1}{\mainFont}{b}{it}
\textSample{T1}{b}{it}

\subsection{Series: m, shape sl}
\xfonttable{T1}{\mainFont}{m}{sl}
\textSample{T1}{m}{sl}

\subsection{Series: b, shape sl}
\xfonttable{T1}{\mainFont}{b}{sl}
\textSample{T1}{b}{sl}

\subsection{Series: m, shape sc}
\xfonttable{T1}{\mainFont}{m}{sc}
\textSample{T1}{m}{sc}

\subsection{Series: m, shape ui}
\xfonttable{T1}{\mainFont}{m}{ui}
\textSample{T1}{m}{ui}

\subsection{Series: m, shape sco}
\xfonttable{T1}{\mainFont}{m}{sco}
\textSample{T1}{m}{sco}

\section{GFS Didot, LGR}
\subsection{Series: m, shape n}
\xfonttable{LGR}{\greekFont}{m}{n}
\textSampleGreek{m}{n}

\subsection{Series: m, shape it}
\xfonttable{LGR}{\greekFont}{m}{it}
\textSampleGreek{m}{it}

\subsection{Series: b, shape n}
\xfonttable{LGR}{\greekFont}{b}{n}
\textSampleGreek{b}{n}

\subsection{Series: b, shape it}
\xfonttable{LGR}{\greekFont}{b}{it}
\textSampleGreek{b}{it}

\subsection{Series: m, shape sl}
\xfonttable{LGR}{\greekFont}{m}{sl}
\textSampleGreek{m}{sl}

\subsection{Series: b, shape sl}
\xfonttable{LGR}{\greekFont}{b}{sl}
\textSampleGreek{b}{sl}

\subsection{Series: m, shape sc}
\xfonttable{LGR}{\greekFont}{m}{sc}
\textSampleGreek{m}{sc}

\subsection{Series: m, shape ui}
\xfonttable{LGR}{\greekFont}{m}{ui}
\textSampleGreek{m}{ui}

\subsection{Series: m, shape sco}
\xfonttable{LGR}{\greekFont}{m}{sco}
\textSampleGreek{m}{sco}
%\clearpage

%\fonttable{didotrg9a} % the basic command
\end{document}