OnSSI is promoting what it calls 'Mix and Match [link no longer available]' that they say will save money on VMS purchases.
Generally, VMS software is offered on multiple tiers, like "Basic", "Medium", "Advanced", at increasingly higher prices. A user typically has to pick the same tier for all cameras.
What OnSSI is offering is to mix and match some cameras at the higher priced "Advanced" level and others at "Basic" or "Medium" on the same system (or in OnSSI's terminology, ES, CS, PS, etc.).
In this note, we break down the potential savings, its application and how it contrasts to Milestone's Interconnect.