A question about Vienna

Does Vienna have a seperate protocol for handling unpaired bases, or does it attempt to mutate all bases equally?

It handles bases that should be paired/unpaired differently.

When it comes to an unpaired base, it randomly mutates.

When it comes to an paired base, it picks 1 of 6 pair types GC,CG,AU,UA,GU,UG randomly and mutate it and its paired base.

Thank you, Jee!