Following topic1 and topic2, I've implemented Mico's answers. Now, I want to reference equations under this enumeration too. For instance,
\documentclass{article}
\usepackage{amsmath}
\usepackage{hyperref}
\usepackage{enumitem,cleveref}
\newlist{myenum}{enumerate}{3}
\setlist[myenum,1]{label=\textbf{\arabic*.},
ref =\arabic*}
\setlist[myenum,2]{label=\textbf{(\alph*)},
ref =\themyenumi.(\alph*)}
\setlist[myenum,3]{label=\bfseries(\roman*),
ref =\themyenumii.(\roman*)}
\numberwithin{equation}{myenumi}
\begin{document}
\begin{myenum}
\item
\begin{equation}\label{eq:euler}
e^{i\pi}+1 = 0
\end{equation}
\end{myenum}
As shown in \cref{eq:euler}.
\end{document}
However, these lines got me this error: "Missing \endcsname inserted. \begin{equation}". Any ideas about why is this happening and/or how to solve this? Thanks.
Edit: I've discovered that this occurs when including the \usepackage{hyperref}
line.
ref =\arabic*
", not "ref =\arabic*.
".