[NTG-context] align header in table

Hi all, I've been following the examples in the garden to write the following table \chardef\characteralignmentmode=1 \startTABLE \setupTABLE[column][alignmentcharacter={,},aligncharacter=yes,align=middle] \setupTABLE[frame=off] \setupTABLE[row][first][bottomframe=on] \NC \alpha \NC \beta \NC error absoluto\NC error relativo \NC \NR \NC 2 \NC 2,1 \NC 0,1 \NC 0,05 \NC \NR \NC 2\times 10\high{-4} \NC 2,1\times 10\high{-4} \NC 0,1\times 10\high{-4} \NC 0,05 \NC \NR \NC 2\times 10\high{4} \NC 2,1\times 10\high{4} \NC 0,1\times 10\high{4} \NC 0,05 \NC\NR \stopTABLE Is there a way to have the entries of first row centered? The obvious \setupTABLE[row][first][align=middle] do not have any effect. Thanks, Jeronimo.