$$abc + \mi{abc} \mo{++} x ++ y$$ $$\ms{Hello world!}$$ $$\mn{\u2460\u2461\u2462}$$ $$ \mi[mathcolor=red]{x} \mi[mathvariant="bold"]{A} \ms[lquote="\u00AB", rquote="\u00BB"]{x} \mi[data-my-attribute="anything"]{x} $$ $$\mi[bad="bad"]{x}$$