-
\subsubsection{PostScript}
Adobe's PostScript Language Reference Manual defines a turing complete language for producing graphics output on an abstract ``output device''\cite{plrm}. A PostScript document is treated as a procedural program; an interpreter executes instructions in the order they are written by the programmer. Each symbol is pushed onto a stack as it is read. Special symbols called ``operators'' can act upon this stack and/or the output device. An internal ``graphics state'' stack can be constructed to store styling information (such as colour, line thickness, the current cursor position). It is possible for the language to define new operators. Figure \ref{PS} shows a vector image and one possible way to express this image in PostScript. PostScript was and is still widely used in printing of documents onto paper; many printers execute postscript directly, and newer formats including PDFs must still be converted into PostScript by printer drivers\cite{pdfref17, cheng2002portable}.
There are some limitations in PostScript's model. As mentioned in Section\ref{Compositing}, since PostScript predates Porter and Duff Compositing, there is no concept of transparency. In fact, using tools to convert between the SVG image in Figure \ref{SVG} and PostScript will simply rasterise the image and embed the rastered image in PostScript\footnote{For Figure \ref{SVG} converted using the Inkscape SVG editor: \url{http://szmoore.net/ipdf/figures/shape-svg-converted-to.ps}}
-Another limitation of PostScript is that the model of a document as a static page, convenient for printers which literally produce static pages, is unable to include interactive or dynamic elements. Dynamic PostScript attempted to fix this problem, but ``never caught on''\cite{hayes2012pixelsor}.
+Another limitation of PostScript is that the model of a document as a static page, convenient for printers which literally produce static pages, is unable to include interactive or dynamic elements. Dynamic PostScript attempted to fix this problem, but ``never caught on''\cite{hayes2012pixels}.
\begin{figure}[H]
\begin{minipage}[t]{0.65\textwidth}
\caption{Vector image and a possible PostScript representation}\label{PS}
\end{figure}
-\subsubsection{\TeX and Metafont}
+\subsubsection{{\TeX}, METAFONT and {\LaTeX}}
-\TeX is a typesetting language invented by Donald Knuth in 1983.
+Knuth's ``The {\TeX}book''\cite{knuth1984texbook} and ``The METAFONT book''\cite{knuth1983metafont} define two complementary programming languages for typesetting documents. Wheras PostScript may be considered an interpreted language, in that it can be produced in a human readable form which is also readable by an interpreter, {\TeX} is a compiled language; a program parses human readable {\TeX} to produce a machine readable format DVI (``DeVice Independent''). A DVI interpreter might be thought of as a virtual ``Display Processor'' for drawing vector graphics directly (as defined in the earlier editions of ``Computer Graphics''\cite{computergraphics2}).
+DVI itself is not a widely used format for sharing documents. However, an system based upon {\TeX} called {\LaTeX} which includes libraries for advanced typesetting and programs that ultimately produce PDF output is particularly popular for producing technical reports and papers\footnote{The site \url{http://tex.stackexchange.com} (accessed 2014-05-22) is devoted to {\TeX} and {\LaTeX}} --- this report itself has been produced using the CTAN {\LaTeX} packages\footnote{The complete {\TeX} source code to produce this document can be found at \url{http://szmoore.net/ipdf/sam/}}.
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