\input plain    % Load Plain TeX macros
\font\tt=cmtt10 % Define a monospace font

% Title
\centerline{\bf Extended Plain TeX Testing Document}
\bigskip
\centerline{\it Test User}
\bigskip
\centerline{Date: \the\year-\the\month-\the\day}
\bigskip

% Table of Contents (simulated with simple text alignment)
\centerline{\bf Contents}
\vskip 10pt
\halign{\hskip 2em #\hfill & \hskip 1em #\hfil\cr
1. Introduction & \dotfill\ Page 2\cr
2. Text Formatting & \dotfill\ Page 2\cr
3. Mathematics & \dotfill\ Page 3\cr
4. Tables & \dotfill\ Page 3\cr
5. Figures & \dotfill\ Page 4\cr
6. Conclusion & \dotfill\ Page 5\cr
}
\eject

% ---------------------- SECTIONS BEGIN -------------------------

\section Introduction
This is an extended test file written in Plain TeX. The intention is to test fundamental typesetting capabilities like text formatting, math equations, tables, and figures in a lightweight and basic TeX environment.

\medskip

\section Text Formatting
You can apply different text styles:

\smallskip
{\bf Bold text}: Produced with {\tt\char`\\bf}. For example, {\bf This is bold text.}\\
{\it Italic text}: Produced with {\tt\char`\\it}. For example, {\it This is italic text.}\\
{\tt Monospaced text}: Produced with {\tt\char`\\tt}. For example, {\tt This is monospaced text.}\\

\medskip
\centerline{\bf Example of Aligning Text:}
\smallskip
\halign{#\hfill\quad&#\cr
Left-aligned text: & This text is aligned to the left.\cr
Center-aligned text: &\hfil This text is centered.\hfil\cr
Right-aligned text: &\hfil This text is aligned to the right.\cr}

\section Mathematics
Inline expressions: \( E = mc^2 \)\\
Displayed equations:
$$
\int_{a}^{b} x^2 \, dx = \frac{b^3}{3} - \frac{a^3}{3}
$$

You can also write matrices and arrays:
$$
\pmatrix{
  a & b \cr
  c & d \cr
}
$$

Mathematical operators look like this:
$$
\sum_{i=1}^n i = \frac{n(n+1)}{2}, \quad
\sqrt{x+y}, \quad
x^2 + y^2 = z^2
$$

\section Tables
Tables are implemented manually in Plain TeX. For example:

\smallskip
\hbox{\vbox{
\hrule
\halign{
\vrule#\quad & #\hfill\quad & \hfil#\quad\vrule\cr
\noalign{\hrule}
\bf Item & \bf Quantity & \bf Price (\$)\cr
\noalign{\hrule}
Apple  & 5  & 3.50\cr
Orange & 3  & 2.25\cr
Banana & 6  & 4.10\cr
\noalign{\hrule}
}
\hrule
}}

\smallskip

For more advanced tables, use external tools or macros.

\section Figures
Including figures in Plain TeX requires external tools like `epsf` or `pdftex` for direct image embedding.

Here’s how you might include an image with a caption:

% \centerline{\hbox{\epsfbox{example-image.eps}}} \centerline{\it Figure 1: Example placeholder image.}

To test without images, you can use placeholders instead:
\medskip
\hbox to \hsize{\hfil \vrule height 2in width 3in \hfil}
\centerline{\it Placeholder for a figure.}

\section Conclusion
This Plain TeX test file demonstrates basic text formatting, math typesetting, tables, and figures. Unlike LaTeX, Plain TeX doesn’t include higher-level structures like environments, so everything is done manually or with custom macros.

% End of test document
\bye