<..equations of amstex.tex..>+
\catcode‘\#=13 \catcode‘\!=6
\def\:tempc!1!2\endalignat{%
\Mk:ialign:end{\preamble@@}{alignat}{!2}#%
{<.amstex.tex alignat get pattern.>%
<.expand amstex.tex ...alignat pattern.>%
}}
\catcode‘\#=6 \catcode‘\!=12
\expandafter\HLet\csname alignat \endcsname\:tempc
\NewConfigure{alignat}{6}
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<..expand amstex.tex ...alignat pattern..>
\def\:temp!!1!!2{\expand:after{!!1!!2}\expandafter}%
\:temp \MkHalign#{\preamble@@}...\EndMkHalign
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<..amstex.tex alignat get pattern..>
\hashtoks@{#}<.inany@true.>\xat@false
<.tag for alignat amstex.tex.>%
\measuring@false \Let@
{\let\@lign=\empty \attag@{!1}}%
\let\allowdisplaybreak =\empty
\pend:def\preamble@@{\:span}%
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<..tag for alignat amstex.tex..>
\def\tag{\global\tag@true\count@!1\relax\multiply\count@\tw@
\xdef\tag@{}\loop\ifnum\count@>\and@\xdef\tag@{&\tag@}%
\advance\count@\m@ne \repeat\tag@}%
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<..equations of amstex.tex..>+
\catcode‘\#=13 \catcode‘\!=6
\def\:tempc!1!2\endxalignat{%
\Mk:ialign:end{\preamble@@}{xalignat}{!2}#%
{<.amstex.tex alignat get pattern.>%
<.expand amstex.tex ...alignat pattern.>%
}}
\catcode‘\#=6 \catcode‘\!=12
\expandafter\HLet\csname xalignat \endcsname\:tempc
\NewConfigure{xalignat}{6}
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<..amstex.tex xalignat get pattern..>
\hashtoks@{#}<.inany@true.>\xat@true
<.tag for xalignat amstex.tex.>%
\measuring@false \Let@
{\let\@lign=\empty \attag@{!1}}%
\let\allowdisplaybreak =\empty
\pend:def\preamble@@{\:span}%
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<..tag for xalignat amstex.tex..>
\def\tag{\global\tag@true\def\tag@{}\count@!1\relax
\multiply\count@\tw@
\loop\ifnum\count@>\and@
\xdef\tag@{&\tag@}\advance\count@\m@ne\repeat\tag@}%
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<..equations of amstex.tex..>+
\catcode‘\#=13 \catcode‘\!=6
\def\:tempc!1!2\endxxalignat{%
\Mk:ialign:end{\preamble@@}{xxalignat}{!2}#%
{<.amstex.tex xxalignat get pattern.>%
<.expand amstex.tex ...alignat pattern.>%
}}
\catcode‘\#=6 \catcode‘\!=12
\expandafter\HLet\csname xxalignat \endcsname\:tempc
\NewConfigure{xxalignat}{6}
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<..amstex.tex xxalignat get pattern..>
\hashtoks@{#}<.inany@true.> \measuring@false \Let@
{\let\@lign=\empty \xxattag@{!1}}%
\let\allowdisplaybreak =\empty
\pend:def\preamble@@{\:span}%
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‘\ifinany@’ and ‘\displaybreak@’ are not defined in ams* starting since 1999.
<..inany@true..>
\ifx \ifinany@\:Undef\else \inany@true\fi
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<..displaybreak@..>
\ifx \displaybreak@\:UnDef
\chardef\dspbrk@context\z@
\else
\displaybreak@
\fi
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<..restore ams equationNO..>
\ifx \ifinany@\:Undef
\HRestore\equation
\HRestore\endequation
\fi
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<..restore amsmath everydisplay..>
\append:def\a:display{\@displaytrue}
\expandafter\append:defIII\csname
c:$$:\endcsname{\append:def\a:display{\@displaytrue}}
-_-_-