Default Exchange Rate ( To Root Subsidiary Primary Book Currency ) > What is this?

Hi!

There's a new field that appeared in the setup of new currencies that I think I have never seen before.

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This rate is the basis for rates in the Currency Exchange Rates table that are used in foreign currency transactions. If you use OneWorld, this rate also is the basis for rates in the Consolidated Exchange Rates table that are used in consolidated financials. 

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Is it not supposed to be the feed from Xignite that will populate this rate? Why is there a need to setup a Default Exchange Rate? And what date should that be referring to?

For additional context, we are implementing a new subsidiary and this was not noticed during our Sandbox testing. In fact, the other currencies didn't have any value for this. But, now it's mandatory and I cannot create a currency without it.