The Open Metering System OMS stands for a manufacturer and utilities independent standardization for Meter-Bus based communication between utility meters (electricity, gas, water, district heat, heat cost allocators) and systems in the field of Smart meter.

Concerning the created Open Metering System Specification (OMS specification or OMSS) a subset out of the existing Meter-Bus standard series (EN 13757) was selected, definitions were made where selections or ambiguities were possible, to streamline the interpretation by different producers.