## Class files

List are basic elements in a document, when used correctly they keep concepts organized and structured. This article explains how to create and modify numbered and unnumbered lists in L a T e X .

# Introduction

Lists are actually very simple to create.

List are really easy to create

\begin{itemize}
\item One entry in the list
\item Another entry in the list
\end{itemize}

To create a (unordered) list you have to declare the itemize environment and then put the entries inside.

# Unordered lists

The unordered (unnumbered) lists are produced by the  itemize  environment. Each entry must be preceded by the control sequence  \item  .

\begin{itemize}
\item The individual entries are indicated with a black dot, a so-called bullet.
\item The text in the entries may be of any length.
\end{itemize}

By default the individual entries are indicated with a black dot, so-called bullet. The text in the entries may be of any length.

# Ordered lists

Ordered list have the same syntax inside a different environment:

\begin{enumerate}
\item The labels consists of sequential numbers.
\item The numbers starts at 1 with every call to the enumerate environment.
\end{enumerate}

The ordered lists are generated by a  \enumerate  environment and each entry must be preceded by the control sequence  \item  , which will automatically generate the number labelling the item. The enumerate labels consists of sequential numbers, these numbers starts at 1 with every call to the enumerate environment.

# Nested Lists

In L a T e X you can insert a list inside another list. The above lists may be included within one another, either mixed or of one type, to a depth of four levels.

\begin{enumerate}
\item The labels consists of sequential numbers.
\begin{itemize}
\item The individual entries are indicated with a black dot, a so-called bullet.
\item The text in the entries may be of any length.
\end{itemize}
\item The numbers starts at 1 with every call to the enumerate environment.
\end{enumerate}

# List styles

As many other L a T e X elements, unordered and ordered list styles can be personalized.

## Ordered lists

The numbering styles change depending on the depth of the nested lists:

 \begin{enumerate}
\item First level item
\item First level item
\begin{enumerate}
\item Second level item
\item Second level item
\begin{enumerate}
\item Third level item
\item Third level item
\begin{enumerate}
\item Fourth level item
\item Fourth level item
\end{enumerate}
\end{enumerate}
\end{enumerate}
\end{enumerate}

The default numbering scheme is:

• Arabic number (1, 2, 3, ...) for Level 1
• Lowercase letter (a, b, c, ...) for Level 2
• Lowercase Roman numeral (i, ii, iii, ...) for Level 3
• Uppercase letter (A, B, C, ...) for Level 4.

These numbers can be changed by redefining the commands that typeset the numbers of various list levels. For example:

 \renewcommand{\labelenumii}{\Roman{enumii}}
\begin{enumerate}
\item First level item
\item First level item
\begin{enumerate}
\item Second level item
\item Second level item
\begin{enumerate}
\item Third level item
\item Third level item
\begin{enumerate}
\item Fourth level item
\item Fourth level item
\end{enumerate}
\end{enumerate}
\end{enumerate}
\end{enumerate}

The command  \renewcommand{\labelenumii}{\Roman{enumii}}  changes the second level to upper case Roman numeral. It is possible to change the labels of any level, replace labelenumii for one of the listed below.

•  \theenumi  for Level 1
•  \theenumii  for Level 2
•  \theenumiii  for Level 3
•  \theenumiv  for Level 4

The command must be placed in the preamble to change the labels globally or right before  \begin{enumerate}  to change labels only in this list. There are some other styles, see the reference guide for a complete list.

In numbered lists the counter is incremented by  \item  before it is printed, and starts from 1,a,i,A,I. This can be changed:

 \renewcommand{\labelenumii}{\Roman{enumii}}
\begin{enumerate}
\item First level item
\item First level item
\begin{enumerate}
\setcounter{enumii}{4}
\item Second level item
\item Second level item
\begin{enumerate}
\item Third level item
\item Third level item
\begin{enumerate}
\item Fourth level item
\item Fourth level item
\end{enumerate}
\end{enumerate}
\end{enumerate}
\end{enumerate}

To change the start number or letter you must use the  \setcounter  command. In the example, to change the start number of level 2 to V the command  \setcounter{enumii}{4}  was used.

To set the start number to any other counter change enumii for any of these:

•  enumi  for Level 1
•  enumii  for Level 2
•  enumiii  for Level 3
•  enumiv  for Level 4

## Unordered lists

The label scheme of unordered lists also changes depending on the depth of the nested list:


\begin{itemize}
\item  First Level
\begin{itemize}
\item  Second Level
\begin{itemize}
\item  Third Level
\begin{itemize}
\item  Fourth Level
\end{itemize}
\end{itemize}
\end{itemize}
\end{itemize}

The default label scheme of itemized list for:

• Level 1 is  \textbullet  (•),
• Level 2 is  \textendash  (–) ,
• Level 3 is  \textasteriskcentered  (*)
• Level 4 is  \textperiodcentered  (·).

These labels can be changed by redefining the commands that typeset them for various list levels. For example, to change Level 1 to black square and Level 2 to white square we'll use :

 \renewcommand{\labelitemi}{$\blacksquare$}
\renewcommand\labelitemii{$\square$}
\begin{itemize}
\item  First Level
\begin{itemize}
\item  Second Level
\begin{itemize}
\item  Third Level
\begin{itemize}
\item  Fourth Level
\end{itemize}
\end{itemize}
\end{itemize}
\end{itemize}

The mathematical symbols used in the previous example belong to the  amssymb  package, so you have to add  \usepackage{amssymb}  to your preamble.

To redefine the label use one of the next commands, depending on the level of list mark you intend to change:

•  labelitemi  for Level 1
•  labelitemii  for Level 2
•  labelitemiii  for Level 3
•  labelitemiv  for Level 4

You can also change the item label for a specific entry, for example:

\begin{itemize}
\item  Default item label for entry one
\item  Default item label for entry two
\item[$\square$]  Custom item label for entry three
\end{itemize}

All you have to do is pass the desired mark as a parameter inside brackets to the item line.

# Reference guide

Available styles for numbered lists:

Code Description
 \alph  Lowercase letter (a, b, c, ...)
 \Alph  Uppercase letter (A, B, C, ...)
 \arabic  Arabic number (1, 2, 3, ...)
 \roman  Lowercase Roman numeral (i, ii, iii, ...)
 \Roman  Uppercase Roman numeral (I, II, III, ...)