There are three kinds of changes documented in this resources.  Zero or more of each kind is included in the change resource.

1. Resources that have been *added* to the booking.  This should only ever be `ChargeItem` resources that carry invoiced codes such as MBS item numbers.  The reference to the added resource is provided as a FHIR reference.
2. Resources that have been *removed* from the booking.  Again, this should only be `ChargeItem` resources.  The identity of the `ChargeItem` is provided as a string as the resource no longer exists so cannot be held in a FHIR reference as the server enforces referential integrity.
3. Resources that have been modified will have a reference to the resource as well as a list of attributes (as strings) that have been changed.  There are a few things to note:
    - `ChargeItem`'s are never changed but rather added or removed.
    - Attributes are described as strings that include the path to the change, i.e. if the change is in a subcomponent of a resource attribute, you will see the flattened path to that attribute.  For example, `name[0].family` for a change to the last name of the first Patient name.
    - Some attribute change descriptions have been modified to replace indexes in lists with more descriptive names.  For example, `contained[Device].deviceName[0].name` identifying a change to a device name within the contained resources of another resource.
