-214 is just an extended range version of the TU
-204. It was originally (and still) known as the TU
From the exterior, it looks no different from a TU
-204. The TU
-214 is really the same aircraft, except with an extra fuel tank, uprated PS
-90А turbofans for a higher MTOW and to compensate for the higher MTOW, its struts were strengthened.
So there is no need for a separate IATA code for it. T20 is just fine.
"Generosity is giving more than you can, and pride is taking less than you need." - Khalil Gibran