I've read up on complex building capabilities before, and I recently downloaded RTR VII Fate of Empires and had a glimpse of this building code:

Code:
upgrades
{
metal_mine1 requires factions { all, } and hidden_resource not_used
metal_mine1 requires factions { counter_faction, mini_faction, britons, } and hidden_resource metal and not building_present_min_level hinterland_raw_materials2 metal_mine2 
metal_mine1 requires factions { counter_faction, mini_faction, britons, } and hidden_resource metal and building_present_min_level hinterland_raw_materials2 precious_metal_mine2
metal_mine1 requires factions { rome_republic, } and building_present_min_level roman_govt roman_govt_2 and hidden_resource metal and not building_present_min_level hinterland_raw_materials2 metal_mine2 
metal_mine1 requires factions { rome_republic, } and building_present_min_level roman_govt roman_govt_2 and hidden_resource metal and building_present_min_level hinterland_raw_materials2 precious_metal_mine2
metal_mine1 requires factions { carthage, } and building_present_min_level carthage_govt_B carthage_govt2 and hidden_resource metal and not building_present_min_level hinterland_raw_materials2 metal_mine2 
metal_mine1 requires factions { carthage, } and building_present_min_level carthage_govt_B carthage_govt2 and hidden_resource metal and building_present_min_level hinterland_raw_materials2 precious_metal_mine2
metal_mine1 requires factions { epirus, } and building_present_min_level epirote_govt epirote_govt_2 and hidden_resource metal and not building_present_min_level hinterland_raw_materials2 metal_mine2 
metal_mine1 requires factions { epirus, } and building_present_min_level epirote_govt epirote_govt_2 and hidden_resource metal and building_present_min_level hinterland_raw_materials2 precious_metal_mine2
metal_mine1 requires factions { gauls, } and building_present_min_level keltoi_govt kelt_govt_2 and hidden_resource metal and not building_present_min_level hinterland_raw_materials2 metal_mine2 
metal_mine1 requires factions { gauls, } and building_present_min_level keltoi_govt kelt_govt_2 and hidden_resource metal and building_present_min_level hinterland_raw_materials2 precious_metal_mine2
metal_mine1 requires factions { spain, } and building_present_min_level iberian_govt iberian_govt_2 and hidden_resource metal and not building_present_min_level hinterland_raw_materials2 metal_mine2 
metal_mine1 requires factions { spain, } and building_present_min_level iberian_govt iberian_govt_2 and hidden_resource metal and building_present_min_level hinterland_raw_materials2 precious_metal_mine2
metal_mine1 requires factions { numidia, } and building_present_min_level base_government numidia_govt_2 and hidden_resource metal and not building_present_min_level hinterland_raw_materials2 metal_mine2 
metal_mine1 requires factions { numidia, } and building_present_min_level base_government numidia_govt_2 and hidden_resource metal and building_present_min_level hinterland_raw_materials2 precious_metal_mine2
}
...
metal_mine1 requires factions { all, } and hidden_resource metal and not building_present_min_level hinterland_raw_materials3 metal_mine3 or factions { all, } and hidden_resource metal and building_present_min_level hinterland_raw_materials3 precious_metal_mine3
{
capability
{
}
...
I'm curious as to why the building code had factions { all, } and ... or factions { all,} and ... because I read up a post a few years back that stated it would not work for the second set of building conditions.