I was browsing the global definitions xml in the game directory and came across a <special>TradeRouteRaidBonus</special> tag and the value is set to .10. Does anyone know what this represents and how this works? I was trying to come up with a way to mod a pirate-like ability for a custom race, and it seems like an ability that adjusts this value might work. But I haven't played enough games to know how raiding trade routes functions in the game.

Edit: I just broke down and got the expansions I needed which already had thematic appropriate abilities. Still curious how it works though.