The initial value of an Integrator, Reservoir, and Pool element must be static. This means that the value cannot change during the simulation and it must not be a function of a dynamic property of GoldSim. This is typically not a problem but there are times when you must refer to data using an expression that is dynamic. For example, what if you wanted to look up a value in a time series by referring to a specific time? This type of function is dynamic and trying to use this in the Store's initial value would cause an error. To get around this, use the Replace feature of a discrete change and link that to the Store element. This model uses this approach for Store type elements, which can be copied into your model.