You describe each of the relations for the vSphere object using RelationSpec objects, which you must create inside the <relationSpecs> property of the ObjectRelationSetSpec extension object. Each RelationSpec object contains information on the relation target object type, display properties such as icons and labels, and any relevant list extensions for the relation target object.RelationSpec Extension Object Properties lists the properties you set for each RelationSpec object.
Unique identifier for the relation. The best practice for creating an ID value for a relation is to use the format [relation target object]For[relation object]. For example, if the parent ObjectRelationSetSpec object defines the relations for Chassis objects, you might use the value hostForChassis as the ID for the RelationSpec object that describes the relation to host objects. Extension ID for a list view that can display the relation target object type. For example, a hostForChassis relation can specify the extension ID of a host list view. The vSphere Web Client uses this list view extension to display the list of related target objects. Relation target object type. For example, in the hostForChassis relation, which displays Host objects related to a selected Chassis object, you specify the <targetType> as HostSystem.Example 8-42, on page 86, presents an example extension definition for a relation extension. In the example, the extension defines relations for the Chassis object type. When the user selects a chassis object, the vSphere Web Client provides related items information for the relations defined in the example. In the example, relations are defined for Rack and Host object types.