Other

eplain/eplain.tex:\def\vfootnote#1{\insert\footins\bgroup
musitex/musixsty.tex:\def\vfootnote#1{\insert\footins\bgroup\parskip\z@\eightpoint
context/base/plain.tex:\def\vfootnote#1{\insert\footins\bgroup
cyrplain/base/cyrplain.tex:\def\vfootnote#1{\insert\footins\bgroup
latex/mathtime/lplain-m.tex:%\def\vfootnote#1{\insert\footins\bgroup
plain/base/plain.tex:\def\vfootnote#1{\insert\footins\bgroup
plain/mathtime/plain-mt.tex:\def\vfootnote#1{\insert\footins\bgroup
plain/misc/mimulcol.tex: \def\vfootnote##1{\insert\footins\bgroup

<..plain vfootnote ..>
\long\def\vfootnote#1{%
    \gHAdvance\FNnum by 1
    \def\FNmark{#1}\ifx \FNmark\empty
       \def\FNmark{*}%
    \fi
    \a:vfootnote\b:vfootnote\bgroup
    \futurelet\:temp\fnt:body}
\def\fnt:body{\ifx \:temp\bgroup \bgroup
       \aftergroup\end:vfootnote\def\:temp{\let\:temp=}%
    \else \def\:temp##1{##1\end:vfootnote}\fi
    \:temp}
\def\end:vfootnote{\egroup\c:vfootnote}
\HAssign\FNnum = 0
\NewConfigure{vfootnote}{3}
-_-_-

The following definition is after manmac, which allows the second parameter to have changes of catcodes. Earlier, we had the following definition.

\long\def\vfootnote#1#2{%
   \gHAdvance\FNnum |by 1 \def\:temp{#1}\ifx \:temp\empty
      \def\:temp##1[##2]##3{##1[##2]{*}}\expandafter\:temp \fi
   \HPageButton[fn\FNnum]{#1}\BeginHPage[fn\FNnum]{ }{#2}\EndHPage{}}

LaTeX does not redefine ‘\vfootnote’. The splited definition of HPage insures that the title of the hypertext will have a blank, and not some possible math commands. An empty parameter in the HPage would put the file name in the title.

<..eplain vfootnote ..>
\long\def\vfootnote#1{%
    \gHAdvance\FNnum by 1 \def\:temp{#1}\ifx \:temp\empty
       \def\:temp##1[##2]##3{##1[##2]{*}}\expandafter\:temp \fi
    \def\FNmark{#1}%
    \a:vfootnote\b:vfootnote\bgroup
    \futurelet\:temp\fnt:body}
\def\fnt:body{\ifx \:temp\bgroup \bgroup
       \aftergroup\end:vfootnote\def\:temp{\let\:temp=}%
    \else \def\:temp##1{##1\end:vfootnote}\fi
    \:temp}
\def\end:vfootnote{\egroup\c:vfootnote}
\HAssign\FNnum = 0
\NewConfigure{vfootnote}{3}
-_-_-