TargetProcess allows to create virtually ANY custom workflow. What you need is a little bit of thinking and creative approach.
Let's look at the communication thread below:
Customer:I want to add a custom field to the story template; I would also like it to be (or not to be) a certain value for the story to be able to be marked done. Thanks.
TargetProcess Team: Can you give us an example of what you're looking for this custom field to be, please?
Customer: I want to make sure that documentation is written before the story is closed. So maybe radio buttons? It could start as "needs documentation" then have options of "documentation written" or "documentation n/a," both of which could be chosen for the case to be able to be closed.
TargetProcess Team: Unfortunately, TargetProcess doesn't allow you to create such a "dependency" on the state of an entity. But you may create custom fields that are "required" fields; forcing someone to pick the status of the documentation (needs, written, or n/a) upon the creation of a user story. You could include "needs doc" as a state before "closed".
As you see, basically, you could juggle with custom fields and custom states to get what you need.