Which are the transformations that are reversible in informatica?

Practically all transformations can be reversible, first  of all it is necessary that this things are placed in the project scope, I am speaking about the what will and what will not put in the project.

When we think in what can be reversible into the application we have think in the register what is necessary to be reversible.

Created a table log, it is possible roll  back virtually all.

Question is not clear. As per my understanding Informatica transformation can be make it as reusable. once transformation made it as reusable , we cannot reverse it.

What do you mean by reversible. Can you explain it.