Something that you would think is moddable and is not. All the values (Defenition, Income and Value) are locked away in the StatType.xsd (Scheme file), while we can add new Strategic resources and Trade resources through the xmls we can not however apply these to anything in game due to this limitation. I am very sad 
Would be nice if you could add a bunch of empty resources, like you have done for invasions, in this scheme. Or better still, port it out into the xmls 
EDIT:
OR OR OR, can we now edit the scheme files?