COMMENT ⊗   VALID 00004 PAGES
C REC  PAGE   DESCRIPTION
C00001 00001
C00002 00002	\chcode'173←1 \chcode'176←2 \chcode'44←3 \chcode'26←4
C00008 00003	\font @=cmathx
C00010 00004	\output{\baselineskip 18pt\page\ctrline{\curfont a\count0}\advcount0}
C00012 ENDMK
C⊗;
\chcode'173←1 \chcode'176←2 \chcode'44←3 \chcode'26←4
\chcode'45←5 \chcode'43←6 \chcode'136←7 \chcode 1←8

\chcode'272←'3072 % this makes formulas like "$x:=x+1$" and "$f:X\to Y$" work

\def\%{\char'45 }	% Note, the space after 45 is needed! (e.g.\%0)

\def\lft#1{#1\hfill}
\def\ctr#1{\hfill#1\hfill}
\def\rt#1{\hfill#1}

\def\rjustline#1{\hbox to size{\hss#1}}
\def\ctrline#1{\hbox to size{\hss#1\hss}}

\def\trace{\chpar0←} \def\jpar{\chpar1←} \def\ragged{\chpar8←}
\def\jjpar{\chpar15←} \def\loose{\chpar14←} \def\uchyph{\chpar16←}

\def\log{\mathop{\char l\char o\char g}\limitswitch}
\def\lg{\mathop{\char l\char g}\limitswitch}
\def\ln{\mathop{\char l\char n}\limitswitch}
\def\lim{\mathop{\char l\char i\char m}}
\def\limsup{\mathop{\char l\char i\char m\,\char s\char u\char p}}
\def\liminf{\mathop{\char l\char i\char m\,\char i\char n\char f}}
\def\sin{\mathop{\char s\char i\char n}\limitswitch}
\def\cos{\mathop{\char c\char o\char s}\limitswitch}
\def\tan{\mathop{\char t\char a\char n}\limitswitch}
\def\cot{\mathop{\char c\char o\char t}\limitswitch}
\def\sec{\mathop{\char s\char e\char c}\limitswitch}
\def\csc{\mathop{\char c\char s\char c}\limitswitch}
\def\max{\mathop{\char m\char a\char x}}
\def\min{\mathop{\char m\char i\char n}}
\def\sup{\mathop{\char s\char u\char p}}
\def\inf{\mathop{\char i\char n\char f}}
\def\det{\mathop{\char d\char e\char t}}
\def\exp{\mathop{\char e\char x\char p}\limitswitch}
\def\Pr{\mathop{\char P\char r}}
\def\gcd{\mathop{\char g\char c\char d}}
\def\choose{\comb()}
\def\leftset{\mathopen{\{\,}}
\def\rightset{\mathclose{\,\}}}
\def\modop{\<\,\mathbin{\char m\char o\char d}\<\,}
\def\mod#1{\penalty0\;(\char m\char o\char d\,\,#1)}
\def\eqv{\mathrel\char'421 }
\def\neqv{\mathrel{\not\eqv}}

\def\qquad{\quad\quad}

\def\ldots{{.\≥.\≥.}}
\def\cdots{{\char'401\≥\char'401\≥\char'401}}
\def\ldotss{{.\≥.\≥.\≥}}
\def\cdotss{\cdots\≥}
\def\ldotsm{{\≥.\≥.\≥.\≥}}
\def\vdots{\vbox{\baselineskip 4pt\vskip 6pt\hbox{.}\hbox{.}\hbox{.}}}

\def\eqalign#1{\baselineskip15pt\lineskip3pt
  \vcenter{\halign{\hfill$\dispstyle{##}$⊗$\dispstyle{\null##}$\hfill
      \cr#1}}}
\def\eqalignno#1{\baselineskip15pt\lineskip3pt
  \vbox{\tabskip 0pt plus 1000pt minus 1000pt
   \halign to size{\hfill$\dispstyle{##}$\tabskip 0pt
   ⊗$\dispstyle{\null##}$\hfill\tabskip 0 pt plus 1000pt minus 1000pt
   ⊗\hfill$ ##$\tabskip 0pt\cr#1}}}
\def\cpile#1{\vcenter{\halign{\hfill$## $\hfill\cr#1}}}
\def\lpile#1{\vcenter{\halign{$## $\hfill\cr#1}}}
\def\rpile#1{\vcenter{\halign{\hfill$## $\cr#1}}}
\def\null{\hbox{}}
\def\twoline#1#2#3{\vbox{\hbox to size{$\quad\dispstyle{#1}$\hfill}
    \vskip#2\hbox to size{\hfill$\dispstyle{#3}\quad$}}}

\def\chop to#1pt#2{\save0\hbox{$\dispstyle{#2}$}\hbox{\lower#1pt\null
    \vbox to 1ht0{\box0\vss}}} % pretends that #2 is #1pt deep

\def\spose#1{\hbox to 0pt{#1\hss}}
\font @=cmathx
\font a=cmr10 \font d=cmr7 \font f=cmr5
\font g=cmi10 \font j=cmi7 \font l=cmi5
\font n=cms10
\font q=cmb10
\font u=cmsy10 \font x=cmsy7 \font z=cmsy5
\font ?=cmti10

\let \curfont=\:
\def\rm{\curfont a} \def\sl{\curfont n} \def\bf{\curfont q} \def\it{\curfont ?}

\parindent 20pt  \maxdepth 2pt  \topbaseline 10pt
\parskip 0pt plus 1 pt  \baselineskip 12pt  \lineskip 1pt
\dispskip 12pt plus 3pt minus 9pt
\dispaskip 0pt plus 3pt  \dispbskip 7pt plus 3pt minus 4pt

\def\biglp{\mathopen{\vcenter{\hbox{\curfont @\char'0}}}}
\def\bigrp{\mathclose{\vcenter{\hbox{\curfont @\char'1}}}}
\def\bigglp{\mathopen{\vcenter{\hbox{\curfont @\char'22}}}}
\def\biggrp{\mathclose{\vcenter{\hbox{\curfont @\char'23}}}}
\def\biggglp{\mathopen{\vcenter{\hbox{\curfont @\char'40}}}}
\def\bigggrp{\mathclose{\vcenter{\hbox{\curfont @\char'41}}}}

\mathrm adf \mathit gjl \mathsy uxz \mathex @
\output{\baselineskip 18pt\page\ctrline{\curfont a\count0}\advcount0}
\setcount0 1

\hsize 353pt % this isn't in the manual but it seems right for the XGP
\vsize 480pt % likewise
\def\hjust{\hbox}\def\vjust{\vbox} % the 1978 names for these things

\rm
\null\vskip-12pt % allows glue at top of first page
% if you want to change \vsize, you have to \eject the first page first