The operations of the transformation API ensure that each CT's actions are logged.

The transaction API built on top of the logging facility is rather simple:

• A rollback undoes all of the logged actions.
• A commit forgets all of the logged actions (so none can be rolled back anymore).

Slightly finer-grained control can be achieved using checkpoints:

• A checkpoint_new marks a point in the logged actions.
• A checkpoint_rollback only rolls back up to a specified checkpoint.
• A checkpoint_commit deletes a check point marker (not the logging information!).

For debugging purposes you can turn on the following:

• toggle_rollback_debug