[Tex/LaTex] \newmdtheoremenv-environment unnumbered

Question

I would like to have a \newmdtheoremenv environment without any number, like I get it from \newtheorem*. How can I do this?

This is my \newmdtheoremenv environment at the moment.

\newmdtheoremenv[outerlinewidth=2,leftmargin=20,%
rightmargin=20,backgroundcolor=blue,%
outerlinecolor=blue,innertopmargin=\topskip,%
splittopskip=\topskip,skipbelow=\baselineskip,%
skipabove=\baselineskip,ntheorem,]{schwartz}%
{The Schwartz-space}

Answer 1

Load the ntheorem package in addition to mdframed and issue \theoremstyle{nonumberplain} before \newmdtheoremenv.

\documentclass{article}

\usepackage{mdframed}
\usepackage{ntheorem}

\theoremstyle{nonumberplain}
\newmdtheoremenv[outerlinewidth=2,leftmargin=20,%
rightmargin=20,backgroundcolor=blue,%
outerlinecolor=blue,innertopmargin=\topskip,%
splittopskip=\topskip,skipbelow=\baselineskip,%
skipabove=\baselineskip,ntheorem,]{schwartz}%
{The Schwartz-space}

\begin{document}

Some text.

\begin{schwartz}
A theorem.
\end{schwartz}

\end{document}