afaik, The term IP Masq was removed going into vCloud Director 5.1.x.
Org Edge Gateways should have an SNAT for the defined internal network, to go external.
However, we do not create a return route (external IP to get inside the network). that's up for you to define.
If you're talking about vApp networks with fencing or connected to an External, then we do a 1:1 NAT (IP Masquerade).