The SameSide class, a special traffic class that measures traffic not destined for the WAN, is automatically created for Inbound and Outbound.
IP addresses that start with "127" are loopback addresses that can be used to ping your own computer or unit.
The address 127.0.0.4 in the SameSide class' matching rule is a bit misleading, though, because it's there just to invoke some PacketWise code.
PacketWise does not actually use 127.0.0.4 to classify SameSide; it is used as an internal pointer for PacketWise to invoke the algorithm to classify SameSide traffic.
Using the hostdb show command, you can see that any IP address on the inside communicating with another IP on the inside is same side (also outside to outside is SameSide).