Stihl "H" & "T" models???

[Orange Wedge]

I stopped by the local Stihl dealer today and he showed me two demo saws he just got from the TimberSports sell off. They were both MS440's and both had decompression valves which he said were going to be standard on the MS440's next year. What threw me and him for that matter was one saw was designated with an "H" and the other was designated with a "T". Does anyone know what the H and T are for???