The Principles And Practice Of Logical Markup In Latex

Defining Logical Structure

Logical structure in LaTeX refers to the semantic markup used to identify different components in a document and their relationships to one another. Examples of logical structures include sections, paragraphs, headings, figures, lists, and math equations. Defining this logical hierarchy is important for organizing content, styling the visual layout, enabling accessibility features, and facilitating maintenance or portability to different output formats.

Logical Design vs Visual Design

In LaTeX, logical structure should be specified separately from visual styling. For instance, a first level heading is marked as \section{} regardless of its font size, alignment, color etc. The visual design can then be controlled through LaTeX packages and class files that format the predefined structures. This separation allows for more consistent structured authoring and output across different target media.

Some key advantages of prioritizing logical design include:

Table of Contents

Consistent, standardized structure independent of styling choices
Ability to rapidly switch visual styles by changing LaTeX style files
Reflowing content to different page sizes or devices while preserving structure
Improved accessibility for assistive technologies, search engines, etc.

Common Logical Markup Packages

Some commonly used packages to extend LaTeX's logical markup capabilities:

\usepackage{amsmath}: For complex mathematical formulas and advanced typesetting capabilities.
\usepackage{amsfonts}: Provides extra mathematical fonts and symbols supporting different mathematical domains.

Titles, Sections and Paragraphs

LaTeX provides a hierarchy of document elements to identify titles, section levels, and paragraphs:

\title{...}: Specifies the document title
\section{...}: Top level section
\subsection{...}: Subsection nested under sections
\paragraph{...}: Lower level paragraph text

These elements can have customized numbering and be formatted differently based on the document class or packages used. For example:

\documentclass[12pt]{article} 
\usepackage{titlesec}

\titleformat{\section}
  {\normalfont\Large\bfseries}{\thesection}{1em}{}
\title{My Article}  

\begin{document}

\maketitle
\section{Introduction}
Text paragraph here...
\subsection{Background}
More text...
\end{document}

Lists and Itemizations

LaTeX supports both unordered and ordered lists:

Unordered lists use the itemize environment:

  
\begin{itemize}
  \item First item
  \item Second item
\end{itemize}

Ordered lists use the enumerate environment:

\begin{enumerate}
  \item First step
  \item Second step
\end{enumerate}

Customization options include changing item labels, indentation, spacing, and more.

Math Environments

LaTeX provides robust support for displaying mathematical expressions via:

Inline math enclosed in $...$ delimiters to embed in text.
Display math surrounded by $$...$$ delimiters to occupy its own line.

Additional advanced environments like equation, align, matrix facilitate precise control over equation layout:

\begin{align}
   a&=b+c \\
   d+e&=f
\end{align}

amsmath and other packages further extend LaTeX's mathematical typesetting capabilities.

Tables and Figures

"Floats" like tables and figures are inserted via:

Table environment: Wraps tabular content
Figure environment: Contains diagram or illustration
\caption{...}: Specifies numbered caption
\label{...}: For cross-referencing float with \ref{}

For example:

\begin{table}[h]
\centering
\begin{tabular}{l|r} 
  Item & Quantity \\\hline
  Apples & 5 \\ 
  Oranges & 10  
\end{tabular}
\caption{Fruit Inventory}  
\label{tab:fruit}
\end{table}

Positioning and alignment options can be specified for optimal placement.

Cross-referencing

Sections, figures and other labeled elements can be cross-referenced:

\label{...}: Assign identifier to section or float
\ref{...}: Insert reference to label
\pageref{...}: Reference page number of a label

Enabling readers to easily trace connections or look up referenced content.

As seen in Figure~\ref{fig:diagram}, the process...

See details in Section~\ref{sec:detail} on page~\pageref{sec:detail}.

Logical Design Principles and Best Practices

Some key principles for effective semantic markup:

Use consistent, standardized markup schemes
Provide clear, unambiguous identifiers for structures
Avoid overlapping or vague structure semantics
Keep presentation separate from logical relationships
Ensure a logical reading order and accessibility

Example structural patterns:

\documentclass{...}
\title{...}
\author{...}  

\begin{document}

\maketitle
\tableofcontents

\section{Introduction}
Text...

\section{Method}
Text... 

\section{Results}

\begin{table}
...
\end{table}

\section{Conclusion}
Text...

\end{document}

With consistent logical markup facilitating redesigns, conversions, or additions.