Missing postNAT fields in netflow v9 flow records

[gnought]

Adding netflow capture on PREROUTING and POSTROUTING chains, I found that the netflow v9 flow record does not contain postNAT fields. They are only in NAT events.

Is it by design? Can those fields be added to get pre-snat and post-dnat information in flow records?

[aabc]

This is consequence of what information is available at the time of reporting a flow (in the iptables target).