Grain Absorption vs. Moisture percentage

Changing the moisture content of a given mash ingredient (grain, etc.) has no affect on the water volumes calculated for the mash.  I can see where you can adjust the global values for grain absorption for sparge and brew-in-a-bag setups, but I would expect that these would be adjusted by the "Moisture" property (in the Grain ingredient window) before coming up with the water volumes.

Is this a bug or an intentional omission?  If the latter, what is the purpose of the "Moisture" parameter?

In my case, this came up when trying to figure out a mash including a large percentage of sweet potatoes.  (contracted to make a gluten-free beer...)  They are extremely high in moisture compared to dried malt, and obviously won't absorb as much (if any) of the water that the software is telling me.  An extreme case perhaps, but one that I'd expect the software to be able to deal with, given that the parameter is there for tweaking.

Hi,
  The moisture parameter in the grain is for informational use and does not impact the water volume calculation.

  The challenge here is that water absorption is not necessarily a function of moisture content (for all possible fermentables).  A sweet potato does not absorb water the same way that crushed barley grain does for example.  I would need a pretty complex model to handle all of these cases.

  So internally the program applies the global grain absorption (though there is a separate global for BIAB due to the bag compression when draining).

Brad