NHibernate: How is identity Id updated when saving a transient instance?

Question

If I use session-per-transaction and call:

session.SaveOrUpdate(entity) corrected:
session.SaveOrUpdateCopy

Answer 1

I noticed I saved by calling:

session.SaveOrUpdateCopy(entity); 

..which does NOT update the Id. But by changing to:

session.SaveOrUpdate(entity);

..the Id's of transient entity will be updated.

I probably misunderstood the documentation (?).. Section 9.4.2 says:

SaveOrUpdateCopy(Object o)... If the given instance is unsaved or does not exist in the database, NHibernate will save it and return it as a newly persistent instance.

Is it just me, or does it not sound like a transient object (unsaved), will be "returned as persistent" ? Doesn't that mean with updated Id? Would appreciate a clarification how to interpret this sentence correctly (?)