% language=us runpath=texruns:manuals/math

\environment math-layout

\startcomponent math-definitions

\startchapter[title=Definitions]

\startsection[title=Special stackers]

There are many math symbols but never enough. Here is an example of how you can
roll out your own. We start out with nothing:

\startbuffer
\definemathstackers
  [nosymbol]
  [voffset=\zeropoint,
   hoffset=\zeropoint,
   mathclass=ord,
   topoffset=\zeropoint,
   middlecommand=,
   color=maincolor]
\stopbuffer

\typebuffer \getbuffer

You can now use this class of stackers:

\startbuffer
\startformula
  \mathover [nosymbol] {"2217} {A}
  \mathover [nosymbol] {"2218} {A}
  \mathover [nosymbol] {"2219} {A}
\stopformula
\stopbuffer

\typebuffer

This looks like this:

\getbuffer

But we want proper math, which means an an italic nucleus, a properly placed
accent, a shift of that accent matching the slope or the nucleus, so we actually
need:

\startbuffer
\definemathstackers
  [mysymbol]
  [voffset=-.30\mathexheight,
   hoffset=\zeropoint,
   mathclass=ord,
   topoffset=.4\mathemwidth,
   middlecommand=\mathematics,
   color=maincolor]
\stopbuffer

\typebuffer \getbuffer

\startbuffer
\startformula
  \mathover  [mysymbol]{"2217}       {A}
  \mathover  [mysymbol]{"2218}       {A}
  \mathover  [mysymbol]{"2219}       {A}
  \mathunder [mysymbol]       {"2217}{A}
  \mathunder [mysymbol]       {"2218}{A}
  \mathunder [mysymbol]       {"2219}{A}
  \mathdouble[mysymbol]{"2217}{"2217}{A}
  \mathdouble[mysymbol]{"2218}{"2218}{A}
  \mathdouble[mysymbol]{"2219}{"2219}{A}
\stopformula
\stopbuffer

We show both over and under variants:

\typebuffer

So this time we get:

\getbuffer

We can now redefine the \quote {interiorset} symbol to use \type {0x2217} instead
of \type {0x2218}:

\startbuffer
\definemathover[mysymbol][interiorset]["2217]

\startformula
    \interiorset{A}^{\interiorset{A}^{\interiorset{A}}}
\stopformula
\stopbuffer

\typebuffer

Of course normally you will not use color:

\pushoverloadmode
\getbuffer
\popoverloadmode

\stopsection

\stopchapter

\stopcomponent