Overview:
Incoming Flow Rate: Returns the number of seconds between flowitems entering a reservoir. This function is executed whenever a flowitem enters. Here the volume of the entering flowitem should be determined. If the reservoir has been full and a flowitem exits and makes space available in the Reservoir, the in flow rate function is executed again from the OnSend event to determine the next time for the flowitem.
Outgoing Flow Rate: Returns the number of seconds between flowitems leaving a reservoir. Usually this function is executed when a flowitem exits, to find the time to release the next flowitem. However, the function is also called for the first flowitem that enters, to get the time to release that flowitem.
Access variables:
current: the current object
isentry: 1 means this function was executed from a flowitem's entry, 0 means it was executed from a flowitem's exit.
item: If isentry is 1, then this is a reference to the flowitem that just entered. Otherwise, it refers to the flowitem that just exited.
unitsnode: This is a reference to a node whose number value can be set to represent a volume for the item. Setting this node's value only applies if isentry is 1 and it is an incoming flow rate trigger, not an outgoing flow rate trigger.
