<..equations of amstex.tex..>+
\let\:tempc=\endmultline
\append:def\:tempc{\b:multline}
\HLet\endmultline=\:tempc
\def\:tempc{\al:gned{multline}}
\HLet\multline=\:tempc
\let\reg:multline=\o:multline:
\NewConfigure{multline}{4}
\let\e:multline=\empty
\let\f:multline=\empty
\catcode‘\#=13 \catcode‘\!=6
\def\:tempc{\let\sv:halign=\halign
\def\halign!!1\crcr{%
\let\halign=\sv:halign
\SaveMkHalignConf:g{multline}%
\MkHalign#{<.multline amstex.tex pattern.>}}%
\o:rmultline@@@:}
\catcode‘\#=6 \catcode‘\!=12
\HLet\rmultline@@@=\:tempc
\def\:tempc{\rmultline@@@}
\HLet\lmultline@@@=\:tempc
\def\:tempc{\crcr\EndMkHalign\RecallMkHalignConfig }
\HLet\lendmultline@=\:tempc
\def\:tempc{\lendmultline@}
\HLet\rendmultline@=\:tempc
-_-_-
<..multline amstex.tex pattern..>
\Let@\hbox{$\m@th\displaystyle\hfil{}#$}%
-_-_-