So, do we have here 4 base categories (Red, Blue, Yellow, Striped) where Orange has both Red and Yellow, Green has both Blue and Yellow and Purple has both Red and Blue. Is India the "has all three categories" since it does seem to have a different base colour than the other blue states?
I further assume that Grey is no data, since I can't imagine anything "infrastructure"-related that will not be found in the grey areas of Europe, Argentinia and New Zealand. I'm still confused that it's apparently linked to cities, yet its states that are coloured.
Something to with modes of transportation (Metro, International Airport, Harbour, etc. ...) or Tallest Buildings?
Just saw that Italy apparently has another shade of blue, now I'm really confused...