\leavevmode
\if !#1!\ht:special{t4ht@+&{35}x#2;}%
\else \expandafter \ifx\csname U#2#1\endcsname\relax
\ht:special{t4ht@+&{35}x#2;}%
\else
\ht:special{t4ht@+&{35}x\csname U#2#1\endcsname;}%
\fi \fi x%
-_-_-
\expandafter\ifx \csname :#1:over\endcsname\relax
\expandafter\ifx \csname :#1:under\endcsname\relax
\AccentMath{<.under over accents.>}%
\else #3\csname :#1:under\endcsname \fi
\else #3\csname :#1:over\endcsname \fi -_-_-
\HCode{<munder\Hnewline
accent="true"><mrow\Hnewline><BREAK SIZE="small"/>}%
#3\HCode{</mrow>}%
\csname :#1:under\endcsname
\HCode{</munder>}%
-_-_-
\HCode{<mover class="mover-accent">%
<mrow\Hnewline><BREAK SIZE="small"/>}%
#3\HCode{</mrow>}%
\csname prefix:#1:over\endcsname
\csname :#1:over\endcsname
\HCode{</mover>}%
-_-_-
\HCode{<munderover\Hnewline
accent="true"><mrow\Hnewline><BREAK SIZE="small"/>}%
#3\HCode{</mrow>}%
\csname :#1:under\endcsname
\csname :#1:over\endcsname
\HCode{</munderover>}%
-_-_-
\def\:temp#1#2{\expandafter\def\csname prefix:#1:over\endcsname
{\HCode{\add:description{added-description}{ #2 }}}}
\:temp{vec}{\b:speak:underover}
\:temp{dddot}{\b:speak:underover}
\:temp{ddddot}{\b:speak:underover}
-_-_-