TFS State transitions: only for GUI use?

Question

The state transitions of a work item in TFS (as defined in the project template): are these used for the workflow logic on the TFS GUI only? Or is this also used as a check when I use the TFS API to make changes to a work item in code?

For example when I remove the transition between Closed and Active (so that the TFS UI will never be able to reactivate a work item), will it still be possible to go from Closed to Active using the API? Or will I get some kind of an exception when I do this?

Answer 1

It is not only for the UI. Also using the API, those state transitions rules are applied.

When you try an invalid state transition, an exception will be returned.