How do I start a list on the second level?

Question

I am using the enumerate environment, and I want to have my lists start on 1.1. instead of 1., and 2.1. instead of 2. How can I hide the first level?

Answer 1

You can either add the numbering locally by using the optional argument to \item[..], or use a global change using enumitem's label=<key>.

\documentclass{article}

\usepackage{enumitem}

\begin{document}

\begin{enumerate}[label={\arabic*.1.}]
  \item First
  \item Second
  \item Third

  % Done with the 1. suffix; revert back to regular enumerate labelling
  \renewcommand{\labelenumi}{\arabic{enumi}.}
  \item Last
\end{enumerate}

\begin{enumerate}
  \item[1.1.] First

  \stepcounter{enumi}
  \item Second

  \item[2.2.] Third

  \item Last
\end{enumerate}

\end{document}

\item-level changes are also possible, like in the first example above, where the labelling mechanism can be changed mid-enumerate to drop (say) the 1. suffix.

Note that using the optional argument to \item doesn't step the level counter enumi.

Answer 2

This uses a mix with manipulation the enumeration depth counter and enumitem and sets the higher level counter enumi accordingly.

\documentclass{article}

\usepackage{etoolbox}
\usepackage{enumitem}

\begin{document}


\makeatletter
\AtEndEnvironment{enumerate}{%
  \global\@enumdepth 0
}

\newcommand{\incenumdepth}[1][1]{%
  \advance \@enumdepth \@ne%
  \setcounter{enum\@roman{\@enumdepth}}{#1}%
}
\makeatother


\incenumdepth[1]
\begin{enumerate}[label*={\arabic*.}]
\item One
\item Two
\item Three
\item Four
\item Five
\end{enumerate}

\incenumdepth[3]
\begin{enumerate}[label*={\arabic*.}]
\item One \makeatletter \the\@enumdepth\makeatother
\item Two
\item Three
\item Four
\item Five
\end{enumerate}


\end{document}