<p><ahref="#Figure_4">Figure 4</a> provides an overview of how to represent a water meter using the <ahref="#s4watr:WaterMeter">s4watr:WaterMeter</a> class. The representation of water meters and their properties has been extracted from the European M-Bus standard (EN 13757).</p>
<p>A water meter may be defined by the properties inherited from SAREF (e.g., <ahref="https://saref.etsi.org/core/hasManufacturer">saref:hasManufacturer</a> or <ahref="https://saref.etsi.org/core/hasModel">saref:hasModel</a>) and also by a set of properties defined in SAREF4WATR to indicate: its fabrication number (<ahref="#s4watr:hasFabricationNumber">s4watr:hasFabricationNumber</a>), its firmware version (<ahref="#s4watr:hasFirmwareVersion">s4watr:hasFirmwareVersion</a>), its hardware version (<ahref="#s4watr:hasHardwareVersion">s4watr:hasHardwareVersion</a>), its version (<ahref="#s4watr:hasVersion">s4watr:hasVersion</a>), the radio frequency in which it operates (<ahref="#s4watr:operatesAtRadioFrequency">s4watr:operatesAtRadioFrequency</a>), and its required power (<ahref="#s4watr:requiresPower">s4watr:requiresPower</a>).</p>
<p>A water meter may be defined by the properties inherited from SAREF (e.g., <ahref="https://saref.etsi.org/core/hasManufacturer">saref:hasManufacturer</a> or <ahref="https://saref.etsi.org/core/hasModel">saref:hasModel</a>) and also by a set of properties defined in SAREF4WATR to indicate: its fabrication number (<ahref="#s4watr:hasFabricationNumber">s4watr:hasFabricationNumber</a>), its firmware version (<ahref="#s4watr:hasFirmwareVersion">s4watr:hasFirmwareVersion</a>), its hardware version (<ahref="#s4watr:hasHardwareVersion">s4watr:hasHardwareVersion</a>), its version (<ahref="https://saref.etsi.org/core/hasVersion">saref:hasVersion</a>), the radio frequency in which it operates (<ahref="#s4watr:operatesAtRadioFrequency">s4watr:operatesAtRadioFrequency</a>), and its required power (<ahref="#s4watr:requiresPower">s4watr:requiresPower</a>).</p>
<p>Observations may be taken from the water meter themselves. To enable the representation of such observations, water meters are defined as features of interest (<ahref="https://saref.etsi.org/core/FeatureOfInterest">saref:FeatureOfInterest</a>) and a non-exhaustive list of properties has been defined based on the M-Bus standard to allow measuring: on time (<ahref="#s4watr:MeterOnTime">s4watr:MeterOnTime</a>), operating time (<ahref="#s4watr:MeterOperatingTime">s4watr:MeterOperatingTime</a>), battery operating time (<ahref="#s4watr:BatteryOperatingTime">s4watr:BatteryOperatingTime</a>), battery last change (<ahref="#s4watr:BatteryLastChange">s4watr:BatteryLastChange</a>), and battery remaining time (<ahref="#s4watr:BatteryRemainingTime">s4watr:BatteryRemainingTime</a>).</p>