Attribute types (previously known as attribute kinds) are the definition of what array of metrics an object type generally supports. Attribute types can be seen as the list of metrics you would expect an object to have, however, there is no guarantee that all objects in the given object type have data for every single attribute. For example, if an administrator selects a virtual machine and wishes to view the Snapshot space used (GB) metric and that VM has never had a snapshot, the No Data message will be displayed in the metrics graph window. Following the same use cases as object types, attribute types are commonly used in super metrics as they allow the formula to be applied to more than one object. One careful consideration when using attribute types in super metrics is that an object may have more than one instance of an attribute. For example, when a VM has more than one CPU or network adapter: