The schema version of the vCloud Air Platform APIs appears in the values of the xmlns attribute in a response.

The version format contains the major and minor versions of the release. For example, a response that used schema version 5.6 would include the following attributes:

xmlns="http://www.vmware.com/vchs/v5.6"
xmlns:tns="http://www.vmware.com/vchs/v5.6"

All requests must include an HTTP Accept header that designates the API version that the client supports. The header indicates that the request is for version 5.6 of the vCloud Air Platform APIs to use with the vCloud API. The following formats are valid for the version:

Accept: application/xml;version=5.6
Accept: application/*;version=5.6 
Accept: */*;version=5.6

Additionally, the combination of the vCloud Air Platform APIs and the vCloud API require that a client obtain the version of the vCloud instance and its API version. Specifically, the client must obtain which version of vCloud is supported by a given vCloud instance. vCloud Air might be deployed with more than one version of the vCloud instance.

vCloud Air can support multiple versions of the vCloud instance. A client can access the vCloud instance deployed with vCloud Air regardless of its version. When a client sends a GET Compute request, the client receives a response containing a VCloudSession element, which includes a VdcRef reference. The VdcRef reference includes an href to the virtual data center.