As in R100T?
Maybe it means something in German, but I've never heard an explanation. As far as I know, the T was only made in 1970 and 80. It was essentially the S model with drum rear brake (a plus in my opinion), no fairing, dual discs, and the cowl-less seat. Supposedly it had a little less power due to lower compression, but the one I have feels plenty powerful - maybe you'd only notice the difference above 100mph.