anchor.diff:  \Doteq,
   \doteqdot,
   \dotplus,
  -\dots,x_1 + \dots + x_n
  -\dotsc,"x,\dotsc,y"
  -\dotsm, (x+1)\dotsm(y-1)
  +\dots,"\begin{array}{c}
  +x_1, \dots, x_n \cr
  +x_1 + \dots + x_n
  +\end{array}"
  +\cdots,
  +\ldots,
  +\dotsb,"\begin{array}{c}
  +\text{dots with binary operations and relations:} \cr\cr
  +x_1 + x_2 +\dotsb + x_n \cr
  +x_1 + x_2 +\dotsb + x_n
  +\end{array}"
  +\dotsc,"\begin{array}{c}
  +\text{dots with commas:} \cr\cr
  +x_1,x_2,\dotsc,x_n \cr
  +x_1,x_2,\dots,x_n
  +\end{array}"
  +\dotsi,"\begin{array}{c}
  +\text{dots with integrals:} \cr\cr
  +\int_{A_1}\int_{A_2}\dotsi\int_{A_n} \cr
  +\int_{A_1}\int_{A_2}\dots\int_{A_n}
  +\end{array}"
  +\dotsm,"\begin{array}{c}
  +\text{dots with multiplication:} \cr\cr
  +x_1x_2\dotsm x_n \cr
  +x_1x_2\dots x_n
  +\end{array}"
  +\dotso,"\begin{array}{c}
  +\text{other dots:} \cr\cr
  +A_1\dotso A_n \cr
  +A_1\dots A_n
  +\end{array}"
   \doublebarwedge,
   \doublecap,
   \doublecup,
  
positive.code: #,\def\specialFrac#1#2{\frac{x + #1}{y + #2}}
  %,%this is a single-line comment
  &,"\begin{matrix}
      a & b\cr
      c & d
      \end{matrix}"
  ^,x^i
  _,x_i
  {,\{
  
negative.code: \large,{\large AaBb123}
  \lbrace,
  \lceil,
  \leadsto,
  \left,\left\lbrace \frac ab, c \right\rbrace
  \leftarrow,
  