  CONST
    nfc$half_minute = 30000000,      {    30,000,000 microseconds }
    nfc$one_minute = 60000000,       {    60,000,000 microseconds }
    nfc$two_minutes = 120000000,     {   120,000,000 microseconds }
    nfc$four_minutes = 240000000,    {   240,000,000 microseconds }
    nfc$eight_minutes = 480000000,   {   480,000,000 microseconds }
    nfc$sixteen_minutes = 960000000, {   960,000,000 microseconds }
    nfc$thirty_minutes = 1800000000; { 1,800,000,000 microseconds }

