Consider the following mapping:
Mapping of Map and GroupLayer
<class name="SharpMap.Layers.GroupLayer, SharpMap" table="grouplayer">
<list name="Layers" lazy="false" cascade="all" collection- type="DeltaShell.Plugins.Data.NHibernate.Collections.Generic.PersistentEventedListType`1[[SharpMap.Layers.ILayer, SharpMap]], DeltaShell.Plugins.Data.NHibernate">
<key column="parent_layer_id"/>
<index column="list_index" />
<one-to-many class="SharpMap.Layers.ILayer, SharpMap"/>
</list>
</subclass>
<class name="Map" table="map" lazy="false" >
<id name="Id" column="id" type="Int64">
<generator class="native" />
</id>
<list name="Layers" lazy="false" cascade="all-delete-orphan" collection-type="DeltaShell.Plugins.Data.NHibernate.Collections.Generic.PersistentEventedListType`1[[SharpMap.Layers.ILayer, SharpMap]], DeltaShell.Plugins.Data.NHibernate">
<key column="map_id"/>
<index column="list_index" />
<one-to-many class="SharpMap.Layers.ILayer, SharpMap"/>
</list>
</class>
As you can see both grouplayer and Map have a list of layers (ILayer) when are mapped in a <list> element. This will result in a 'schema' like this:
