It is often necessary or useful to define groups of monitoring features, for example when there are several monitoring points at a particular site or station.<br /></p><p><br /></p><p>The ISO 19156 <i>SF_SamplingFeatureCollection </i>provides this grouping mechanism. A group can be defined in one of two ways:<br /></p><p><br /></p><p><ul><li>By including a relationship from the sampling feature (MonitoringFeature) to the group using the <i>relatedSamplingFeature</i> property of the sampling feature. </li><br /></p><p><li>By defining a <i>SF_SamplingFeatureCollection</i> that contains the sampling points. This can be done by defining the points inline of the collection or by referencing pre-defined sampling points using an identifier. </li><br /></p><p></ul><br /></p>