Several of you asked me about NAT types. I responded that a NAT may perform different kinds of translation (i.e., use different algorithms to update an outgoing packet's source IP address) , and that's why we have multiple NAT types.
Here's a document that discusses these NAT types in detail:
https://www.juniper.net/documentation/en_US/junos/topics/topic-map/nat-security-source-and-source-pool.html
Being a bit surprised at the unusual interest in NAT types, I searched around a bit, and I found that another meaning of the term "NAT type" has emerged (Open/Moderate/Strict or Type1/Type2/Type3), typically relevant in the context of gaming. This doesn't have anything to do with the NAT types I had in mind. I will investigate, and we will discuss next time we meet.