\starttext

% beware, we have a \noindent so an empty line is indeed an empty line

\startTEXpage[offset=0.5ex,align={lohi,middle}]

    \vbox{\hbox{x}}
\stopTEXpage

\startTEXpage[offset=0.5ex,align={lohi,middle}]
    \vbox{\hbox{x}}
\stopTEXpage

\stoptext
