Port forwarding question

I'm having difficulty understanding this.

clive@Southwater-192-168-14-254# show service nat
 rule 1 {
     destination {
         address 192.168.1.13
         group {
             port-group SSH2222
         }
     }
     inbound-interface eth0
     inside-address {
         address 192.168.14.23
         port 22
     }
     log disable
     protocol tcp
     type destination
 }
 rule 5010 {
     description "Masquerade for WAN"
     outbound-interface eth0
     type masquerade
 }
[edit]
clive@Southwater-192-168-14-254# show port-forward
 auto-firewall enable
 hairpin-nat enable
 lan-interface eth1.1
 rule 1 {
     description "SSH to laptop"
     forward-to {
         address 192.168.14.23
         port 22
     }
     original-port 2222
     protocol tcp
 }
 wan-interface eth0
[edit]
clive@Southwater-192-168-14-254#

This seems to work. No firewall rules have been set that would allow or deny this.

My question is why do I need both parts? If I delete either section it stops working.
Is there a better way to accomplish it?