+The process of creating and displaying a document is a rather universal one (\ref{documenttimeline}), though
+different document formats approach it slightly differently. A document often begins as raw content: text and images
+(be they raster or vector) and it must end up as a set of photons flying towards the reader's eyes.
+
+\begin{figure}
+ \label{documenttimeline}
+ \centering \includegraphics[width=0.8\linewidth]{figures/documenttimeline}
+ \caption{The lifecycle of a document}
+\end{figure}
+
+There are two fundamental stages by which all documents --- digital or otherwise --- are produced and displayed:
+\emph{layout} and \emph{rendering}. The \emph{layout} stage is where the positions and sizes of text and other graphics are
+determined. The text will be \emph{flowed} around graphics, the positions of individual glyphs will be placed, ensuring
+that there is no undesired overlap and that everything will fit on the page or screen.
+
+The \emph{display} stage actually produces the final output, whether as ink on paper or pixels on a computer monitor.
+Each graphical element is rasterized and composited into a single image of the target resolution.
+
+
+Different document formats cover documents in different stages of this project. Bitmapped images,
+for example, would represent the output of the final stage of the process, whereas markup languages typically specify
+a document which has not yet been processed, ready for the layout stage.
+
+Furthermore, some document formats treat the document as a program, written in
+a (usually turing complete) document language with instructions which emit shapes to be displayed. These shapes are either displayed
+immediately, as in PostScript, or stored in another file, such as with \TeX or \LaTeX, which emit a \texttt{DVI} file. Most other
+forms of document use a \emph{Document Object Model}, being a list or tree of objects to be rendered. \texttt{DVI}, \texttt{PDF},
+\texttt{HTML}\footnote{Some of these formats --- most notably \texttt{HTML} --- implement a scripting lanugage such as JavaScript,
+which permit the DOM to be modified while the document is being viewed.} and SVG\cite{svg2011-1.1}. Of these, only \texttt{HTML} and \TeX typically
+store documents in pre-layout stages, whereas even turing complete document formats such as PostScript typically encode documents
+which already have their elements placed.
+
+\begin{description}
+ \item[\TeX \, and \LaTeX]
+ Donald Knuth's typesetting language \TeX \, is one of the older computer typesetting systems, originally conceived in 1977\cite{texdraft}.
+ It implements a turing-complete language and is human-readable and writable, and is still popular
+ due to its excellent support for typesetting mathematics.
+ \TeX only implements the ``layout'' stage of document display, and produces a typeset file,
+ traditionally in \texttt{DVI} format, though modern implementations will often target \texttt{PDF} instead.
+
+ This document was prepared in \LaTeXe.
+
+ \item[DVI]
+ \TeX \, traditionally outputs to the \texttt{DVI} (``DeVice Independent'') format: a binary format which consists of a
+ simple stack machine with instructions for drawing glyphs and curves\cite{fuchs1982theformat}.
+
+ A \texttt{DVI} file is a representation of a document which has been typeset, and \texttt{DVI}
+ viewers will rasterize this for display or printing, or convert it to another similar format like PostScript
+ to be rasterized.
+
+ \item[HTML]
+ The Hypertext Markup Language (HTML)\cite{html2rfc} is the widely used document format which underpins the
+ world wide web. In order for web pages to adapt appropriately to different devices, the HTML format simply
+ defined semantic parts of a document, such as headings, phrases requiring emphasis, references to images or links
+ to other pages, leaving the \emph{layout} up to the browser, which would also rasterize the final document.
+
+ The HTML format has changed significantly since its introduction, and most of the layout and styling is now controlled
+ by a set of style sheets in the CSS\cite{css2spec} format.
+
+ \item[PostScript]
+ Much like DVI, PostScript\cite{plrm} is a stack-based format for drawing vector graphics, though unlike DVI (but like \TeX), PostScript is
+ text-based and turing complete. PostScript was traditionally run on a control board in laser printers, rasterizing pages at high resolution
+ to be printed, though PostScript interpreters for desktop systems also exist, and are often used with printers which do not support PostScript natively.\cite{ghostscript}
+
+ PostScript programs typically embody documents which have been typeset, though as a turing-complete language, some layout can be performed by the document.
+
+ \item[PDF]
+ Adobe's Portable Document Format (PDF)\cite{pdfref17} takes the PostScript rendering model, but does not implement a turing-complete language.
+ Later versions of PDF also extend the PostScript rendering model to support translucent regions via Porter-Duff compositing\cite{porter1984compositing}.
+
+ PDF documents represent a particular layout, and must be rasterized before display.
+\end{description}
+
+\subsection{Precision in Document Formats}
+
+Existing document formats --- typically due to having been designed for documents printed on paper, which of course has
+limited size and resolution --- use numeric types which can only represent a fixed range and precision.
+While this works fine with printed pages, users reading documents on computer screens using programs
+with ``zoom'' functionality are prevented from working beyond a limited scale factor, lest artefacts appear due