recovery and resetlogs

I have a question regarding instance and database recovery and their interaction with a resetlogs operation.

I understand that instance recovery is a two-phase process, where SMON first rolls-forward all redo, opens the database, and then goes into a low-priority background state and rolls-back all uncommitted redo.

However, when the database is recovered from backup datafiles without online redo logs (by rolling through archived logs), and the database is opened with a resetlogs operation, how does SMON know about the uncommitted transactions?

I imagine that rolling-forward through the redo built all required versioning blocks in the rollback segments, but when all redo records are erased, how does SMON still retain knowledge of uncommitted transactions?

   / Charles J. Fisher                   |"How many who came into this world /
  /  cfisher_at_rhadmin.org                 | with me have already left it!"   /
 /   http://rhadmin.org                  |       -Marcus Aurelius          /
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