\setuppapersize     [A5][A4]
\setuplayout        [location=middle,marking=on] 
\setuppagenumbering [alternative=singlesided]
\setupbodyfont      [lbr,6pt]
\setupheadertexts   [alfa][beta]

\showframe

\starttext 
  \dorecurse{10}{\input tufte \par \input knuth \par} 
\stoptext
