At first, the equation driven curve has to be in black, since it's totally defined.

At second, the dim D6@sketch2 has to be amnnouced like a driven dimension, since this angle is totally defined by the EDC, which is also totally defined.

But things don't end here, and there is much more funny : I change t1 to 0, then the EDC changes, in the parametric definition of the EDC and the first changing is OK.

But if I redefine t1="t1", the EDC begins to be a bit not driven, but obviously drunken.

Would be some limit to this drunkard's walk Markov chain ?

Alternating t1 =0 and t1="t1", yes, there is some limit.

Moral : the connerie of the  SW  team is ergotic.