I would like to have bold enumerate labels that both have a Roman numeral and a custom text in them, like on page 26 (pdf page 2) of http://www.ams.org/bookstore/pspdf/stml-48-prev.pdf.
I'm using the following code to just have bold Roman numerals (using enumitem), but I can't figure out how to add custom text.
\documentclass{article}
\usepackage{enumitem}
\begin{document}
\begin{enumerate}[label=\textbf{\Roman*}]
\item item one.
\item item two.
\end{enumerate}
\end{document}
How can this be done?

