mBits &= ~COL_SPAN;
mBits &= ~COL_SPAN_0;
inline void CellData::SetZeroColSpan(PRBool aIsZeroSpan){  if (SPAN == (SPAN & mBits)) {    if (aIsZeroSpan) {      mBits |= COL_SPAN;    }    else {      mBits &= ~COL_SPAN;    }  }}