\ifxetex
\RequirePackage[quiet]{fontspec}
% To support LaTeX quoting style
\defaultfontfeatures{Ligatures=TeX}
\else
\RequirePackage[T1]{fontenc}
% Replace by the encoding you are using
\RequirePackage[utf8]{inputenc}
\fi
% Needed to manage math fonts
\RequirePackage[math-style=TeX,vargreek-shape=unicode]{unicode-math}
That doesn't make any sense.