\@primitives{amsfonts}
\def\mathbb{\apply@chars{\one@mathbb}}
\def\frak{\apply@chars{\one@frak}}
\DeclareSymbolHtml{\ulcorner}{X231C}
\DeclareSymbolHtml{\urcorner}{X231D}
\DeclareSymbolHtml{\llcorner}{X231E}
\DeclareSymbolHtml{\lrcorner}{X231F}
