Zero View for Adjustments and Zero View For Non-Adjustments use

First of all, the attribute applies only to flow accounts (revenue, expense, and flow). The setting tells HFM how to interpret missing values. For the vast majority of HFM applications, Actual data is loaded YTD. For performance reasons we do not want to load zeros, and so we suppress them in the data load process. If a cell had a value last month, and there is no value in the current month, a setting of "YTD" tells HFM that the missing value should be interpreted as YTD zero. In order to accomplish this, HFM will derive a negative value on a Periodic basis, in order to arrive at a YTD zero.
The same holds true for data coming from journals. If you post a journal to an intersection in one period, and do not post any journals to the same intersection in the next period, the ZeroViewForAdjs setting "YTD" tells HFM to derive a negative number in the adjustment node to arrive at a YTD zero for the intersection. This is the main reason why most HFM users don't need reversing entries -- HFM will reverse the vast majority of adjustments based on this setting.
When either is set to Periodic, the situation is very different. HFM will intepret the missing data as a Periodic zero, and on a YTD basis it will simply carry forward the previous period's YTD amount. This is most common for Periodic scenarios such as Budget or Forecast.