Value rollups can be done on recipes as well as on reported events. They summarize the values of all of the inputs to all of the processes that go into the creation of a Resource Category or an Economic Resource.
In business, cost rollups on recipes (usually bills of material and routings) calculate the Standard Cost of producing a commercial product model. Then actual cost rollups, summarizing the actual events that went into creating a product instance, can be compared to the standard cost.
In value networks, value rollups can be done in both of those same ways (standard value and actual value), but all of the input values need to be converted into the same unit: often, but not necessarily, a unit of money. In a time bank system, the unit would be hours. In a mutual credit system, the unit could be hours, or it could be whatever the credits represent.