We have a management agent that creates a CSV every time it is run.  There are never any updates/deletions, only "Adds".  The issue is that I'm trying to remove a symbol (the "+") from the phone numbers when it is exported, but from what I'm reading only during synchronization (i.e. not projection/creation) can I use special rules in creation.  Is this correct?

Hello Gareth,

No, you can use extension rules for your export attribute flow (but yes it will be apply during the synchronization run profile, because export  run profile only set values without any computing and import run profile only get values without any computing)

See this for Export Attributes Flow mapping

Regards,