Hi,
Why is the height of the cells of the third line different ?
Thank you.
Fabrice

\starttext
 \startxtable[align={lohi,middle},offset=0.8ex,width=3cm]
        \startxrow
          \startxcell
            \m{x}
          \stopxcell
          \startxcell[nx=3]
            \math{-\infty} \hfill \math{+\infty}
          \stopxcell
        \stopxrow
        \startxrow
          \startxcell
            Signe de \m{3x-6}
          \stopxcell
          \startxcell
            \unknown
          \stopxcell
          \startxcell
            \unknown
          \stopxcell
          \startxcell
            \unknown
          \stopxcell
        \stopxrow
        \startxrow
          \startxcell
            Signe de \m{-2x+8}
          \stopxcell
          \startxcell
            \unknown
          \stopxcell
          \startxcell
            \unknown
          \stopxcell
          \startxcell
            \unknown
          \stopxcell
        \stopxrow
        \startxrow
          \startxcell[width=6cm]
            Signe de \m{(3x-6)(-2x+8)}
          \stopxcell
          \startxcell
            \unknown
          \stopxcell
          \startxcell
            \unknown
          \stopxcell
          \startxcell
            \unknown
          \stopxcell
        \stopxrow
      \stopxtable
\stoptext