[NTG-context] \bTD\numexpr\currentTABLErow\minusone\relax\eTD

Hello, I naively tried using \bTD\numexpr\currentTABLErow\minusone\relax\dTD in a TABLE. As I do not master even simple calculations under TeX, I do not see what I am missing in order to label TABLE rows, starting from 0? (Row 1 is a heading, set off by \bTABLEhead\eTABLEhead, which is why I am looking to subtract 1 from \currentTABLErow, but this does not matter of course. But perhaps the addressing of TABLE rows, including within \setupTABLE, should or could handle this situation? This is a secondary question to think about...) Alan