--- /dev/null
+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. In particular, the document specifies the locations of enclosed curves using B\'{e}zier splines (Section \ref{}), whilst text is treated as vector fonts described in Section \ref{}.
+\begin{comment}
+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.\end{comment}
+PostScript was and is still widely used in printing of documents onto paper; many printers execute postscript directly, and newer formats including PDF must still be converted into PostScript by printer drivers\cite{pdfref17, cheng2002portable}.
+
+
+
+Adobe's Portable Document Format (PDF) is currently used almost universally for sharing documents; the ability to export or print to PDF can be found in most graphical document editors and even some plain text editors\cite{cheng2002portable}.
+
+Hayes describes PDF as ``... essentially 'flattened' PostScript; it’s what’s left when you remove all the procedures and loops in a program, replacing them with sequences of simple drawing commands.''\cite{hayes2012pixels}. %Consultation of the PDF 1.7 standard shows that this statement does not a give a complete picture --- despite being based on the Adobe PostScript model of a document as a series of ``pages'' to be printed by executing sequential instructions, from version 1.5 the PDF standard began to borrow some ideas from the Document Object Model.
+
+%For example, interactive elements such as forms may be included as XHTML objects and styled using CSS. ``Actions'' are objects used to modify the data structure dynamically. In particular, it is possible to include Javascript Actions. Adobe defines the API for Javascript actions seperately to the PDF standard\cite{js_3d_pdf}. There is some evidence in the literature of attempts to exploit these features, with mixed success\cite{barnes2013embedding, hayes2012pixels}.
+
+%Figure \ref{PS} shows a vector image and one possible way to express this image in PostScript.
+
+%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{hayes2012pixels}.
+
+\begin{comment}
+\begin{figure}[H]
+\begin{minipage}[t]{0.65\textwidth}
+\begin{minted}{postscript}
+%!PS-Adobe-3.0 EPSF-3.0
+%%BoundingBox: 0 -1 85 150
+% These lines are comments to aid in human understanding
+% Define an operator to produce a rectangular path
+/re { exch dup neg 3 1 roll 5 3 roll moveto 0 rlineto
+ 0 exch rlineto 0 rlineto closepath } bind def
+% Operator to produce the path for the first rectangle
+/re1 { 24.613 133.001 24 -120 re } bind def
+% Operator to produce the path for the second rectangle
+/re2 { 10.215 45.001 48 -16 re } bind def
+% Operator which will produce the curved path
+/curve { 46.215 1.001 moveto
+ 46.215 1.001 91.812 11.399 71.812 35.399 curveto
+ 51.812 59.399 29.414 33.802 51.812 59.399 curveto
+ 74.215 85.001 93.414 45.802 74.215 85.001 curveto
+ 55.016 125.001 61.414 49.802 46.215 75.399 curveto
+ 31.016 101.001 56.613 126.598 56.613 126.598 curveto
+ 56.613 126.598 88.613 166.598 56.613 137.802 curveto
+ 24.613 109.001 -18.586 83.399 9.414 50.598 curveto
+ 37.414 17.802 45.414 1.001 45.414 1.001 curveto
+closepath } bind def
+% Set stroke properties
+0.8 setlinewidth 0 setlinecap 0 setlinejoin []
+ 0.0 setdash 4 setmiterlimit
+% Draw the straight line
+0 setgray 0.613 149.001 moveto 83.812 0.2 lineto fill
+% Fill and outline the first rectangular path
+0 0 1 setrgbcolor re1 fill 0 setgray re1 stroke
+% Fill and outline the curved shape
+1 0 0 setrgbcolor curve fill 0 setgray curve stroke
+% Fill and outline the second rectangle
+0 1 0 setrgbcolor re2 fill 0 setgray re2 stroke
+showpage
+\end{minted}
+\end{minipage}
+\begin{minipage}[t]{0.3\textwidth}
+ \begin{figure}[H]
+ \centering
+ \includegraphics[width=1\textwidth]{figures/shape.eps}
+ \end{figure}
+\end{minipage}
+ \caption{Vector image and a possible PostScript representation}\label{PS}
+\end{figure}
+
+
+\subsubsection{{\TeX}, METAFONT and {\LaTeX}}
+
+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/}}.
+\end{comment}
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