Custom views Envelope offset

Hi, I am experimenting with the custom views early access feature. I notice that the Envelope has an offset but it is optional. In what cases will there be no offset on an Envelope? I’d like to have access to the transaction offset for every Event inside my Project function, is this possible?

It’s None during the ACS ingestion initially. It’s set for transactions afterwards.

I thought that the tool would use getTransactions instead of using ACS? Quoting the docs - “A newly created projection by default has no offset, which means a projection starts from the beginning of the ledger”. That seems to imply it would initially stream transactions from the ledger beginning, rather than getting the ACS?

I believe the docs are off there. If the offset is not set, it starts from the ACS not from ledger beginning.