$$
      \enclose{box}{x}
      \enclose{unknown}{x}
      \enclose{bottom,circle,top}{x}
      \enclose{bottom}[color=red,background=blue]{x}
      \enclose{bottom}[mathcolor=red,mathbackground=blue]{x}
      \enclose{updiagonalstrike}[arrow=1]{x}
$$
