What is a Top Regulator?
A Top Regulator is a variable upstream water source. A Top Regulator is used as the starting point for network traversal, which DMS performs for demand calculations, for discovering network objects, and for reporting.
An Up Regulator is a regulator at the upstream boundary of an area, so a Top Regulator is always an Up Regulator. However, some Up regulators are setflows, for which planners manually set a flow rate. Network traversal always stops at a setflow, so you should not mark a setflow regulator as a top regulator.
See Setflows Module for more details.