Originally Posted by
rpenmanparker
Why. What good does it do you? Except in the cases where the reviews tell you something is the same or different from something else, it is really of no importance. Different is different. It can't be rigged to be the same.
He's just trying to figure out a compatibility chart for mix 'n match groups. That can be important if he buys the current Tiagra levers and finds out that they can't shift a 6600 RD correctly even though they're both 10 speed parts, ect.