Project Task Dates vs PO Dates

Summary: I need some help understanding how the transaction start and finish dates on a task work in conjunction with requisitions and receipting on a PO.

Here are the things I believe to be true:

• The date a good or service is receipted is the expenditure item date in PPM
• The transactions start and finish dates on a task in PPM typically are what would stop a user from selecting a given Project and/or task outside of the set dates

Recently, I have run into a couple of situations the PO receipt was also outside of the date range and yet…it was imported to the project without error.