For example, there are 6 hidden_resource "tripoli", "muscat", "venice", "lisbon", "stettin" and "bruges" used in order to apply wonders(?) "tripoli_port", "muscat_port", "venice_port", "lisbon_port", "stettin_port" and "bruges_port".
Now instead of declaring these 6 hidden_resource directly, we can declare 4 hidden_resource "port_wonder", "port_a", "port_b" and "port_c".
And in descr_regions.txt, these 6 regions now have hidden_resource
Tripoli : port_wonder
Muskat : port_wonder, port_a
Venice : port_wonder, port_b
Lisbon : port_wonder, port_c
Stettin : port_wonder, port_a, port_b
Bruges : port_wonder, port_a, port_c
So back to EDB we have
hidden_resource tripoli → hidden_resource port_wonder and not hidden_resource port_a and not hidden_resource port_b and not hidden_resource port_c
hidden_resource muscat → hidden_resource port_wonder and hidden_resource port_a and not hidden_resource port_b and not hidden_resource port_c
hidden_resource venice → hidden_resource port_wonder and not hidden_resource port_a and hidden_resource port_b and not hidden_resource port_c
hidden_resource lisbon → hidden_resource port_wonder and not hidden_resource port_a and not hidden_resource port_b and hidden_resource port_c
hidden_resource stettin → hidden_resource port_wonder and hidden_resource port_a and hidden_resource port_b and not hidden_resource port_c
hidden_resource bruges → hidden_resource port_wonder and hidden_resource port_a and not hidden_resource port_b and hidden_resource port_c
The function is the same, but number of hidden_resource required is 2 less then before.
Now we only have 62 hidden_resource, and can feel free to add "spices" as the 63rd.