bit_write_BT (Bit_Chain *dat, double value)
{
  if (dat->version >= R_2000 && value == 0.0)
    bit_write_B (dat, 1);
  else
    {
      bit_write_B (dat, 0);
      bit_write_BD (dat, value);
    }
}
bit_write_BT (Bit_Chain *dat, double value)
{
  if (dat->version >= R_2000 && value == 0.0)
    bit_write_B (dat, 1);
  else
    {
      bit_write_B (dat, 0);
      bit_write_BD (dat, value);
    }
}