8.2 Choose

<..plain,latex math..>+
 \def\atop:choose#1#2#3{\a:choose}
 \def\:temp{%
    \expandafter \ifx\csname a:choose\endcsname\relax \else
    \ifx\a:choose\empty \else
       \Configure{atopwithdelims}{\atop:choose}{}%
    \fi\fi
    \o:choose:}
 \HLet\choose=\:temp
 \NewConfigure{choose}{1}
 -_-_-

<..body of amsmath.sty..>
 \def\above:tbinom#1#2#3#4{\a:tbinom}
 \def\:temp{%
    \expandafter \ifx\csname a:tbinom\endcsname\relax \else
    \ifx\a:tbinom\empty \else
       \Configure{abovewithdelims}{\above:tbinom}{}%
    \fi\fi
    \o:tbinom:}
 \HLet\tbinom\:temp
 \NewConfigure{tbinom}{1}
 -_-_-

<..body of amsmath.sty..>+
 \def\above:dbinom#1#2#3#4{\a:dbinom}
 \def\:temp{%
    \expandafter \ifx\csname a:dbinom\endcsname\relax \else
    \ifx\a:dbinom\empty \else
       \Configure{abovewithdelims}{\above:dbinom}{}%
    \fi\fi
    \o:dbinom:}
 \HLet\dbinom\:temp
 \NewConfigure{dbinom}{1}
 -_-_-

<..body of amsmath.sty..>+
 \def\above:binom#1#2#3#4{\a:binom}
 \def\:temp#1{%
    \def\:temp{%
       \expandafter \ifx\csname a:binom\endcsname\relax \else
       \ifx\a:binom\empty \else
          \Configure{abovewithdelims}{\above:binom}{}%
       \fi\fi
       #1}}
 \expandafter\:temp\expandafter{\csname o:binom :\endcsname}
 \expandafter\HLet\csname binom \endcsname\:temp
 \NewConfigure{binom}{1}
 -_-_-