\usepackage[en-GB,en-US]{datetime2} \newcommand*{\teststyle}[1]{% \DTMsetstyle{#1} \texttt{#1}:\par \DTMnow\par \DTMNow\par } \newcommand*{\testall}[1]{% \DTMlangsetup*{#1} \texttt{#1}:\par \teststyle{default} \teststyle{iso} \teststyle{english} \teststyle{en-GB} \teststyle{en-GB-numeric} \teststyle{en-US} \teststyle{en-US-numeric} \teststyle{french} \teststyle{french-numeric} } \begin{document} \testall{showdayofmonth=true,abbr=false} \testall{showdayofmonth=false} \testall{abbr=true} \end{document}