"LAN net" in firewall rules for interface with multiple subnets

[davide]

I configured the LAN interface with multiple CARP IP coming from different subnet (192.168.250.1/24 and 10.100.0.1/27).

Instead of adding two rules (one with source 192.168.250.0/24 and the other with source 10.100.0.0/27), adding only one rule with source "LAN net" works but I wish to know if there is an explanation of how "LAN net" is constructed.

Thank you