States that BACnet is the most practical option for achieving real interoperability of automation systems at a system (non-sensor/field bus) level. Explains its importance to specifying engineers in that, as an American National Standard, BACnet creates a safe and robust method for specifiers to ensure intersystem interoperability, while remaining open and flexible to accommodate different approaches between vendors. Considers where BACnet is appropriate. Goes on to list and refute current misconceptions about BACnet, namely - 'BACnet is only useful in large systems, specifying interoperability with BACnet is difficult, Nobody really needs interoperability, BACnet is all pie in the sky and not down to earth.' Supplies web site addresses providing insights and useful information for specifiers.