DDEX standard message formats are used to carry information from one company to another. They do so by clearly defining the semantics of each “tag” as well as, where appropriate, the value that is communicated. The
UseType tag, for instance provides information about how a consumer is allowed to interact (or has interacted) with a Release or Resource. This tag can carry a number of DDEX-defined allowed values such as "download":
Users of the DDEX standards should only use user-defined values when DDEX does not provide any suitable values for their purpose as user-defined values drastically reduce compatibility.
If there is no suitable DDEX-defined value available, users should attempt to specialise a DDEX term and only revert to using stand-alone user-defined values as a last resort.
Users of the standards should also contact DDEX to work towards adding any non-confidential user-defined values into future versions of the DDEX standards.
DDEX, in its data dictionary, clearly defines what the
Download means in order that both the sender and receiver of a message know what is intended to be communicated.
In some cases it may be necessary, however, to communicate a term that is not, at that time, defined by DDEX. If, for example,
a record company X, wants to only allow a Release to be accessed by consumers on Mondays, X can agree with its business partners to use the term
AccessOnMondays to convey that meaning. However, to ensure that there is no conflict or overlap between X’s definition of
AccessOnMondays with another company’s definition of
AccessOnMondays, a “namespace” needs to be added:
As shown in the example, this namespace identifier should take the form of the DDEX Party Identifier (DPID) of the company that has created the term and definition. The
Namespace attribute should not contain the namespace prefix “DPID:”.
If the company that has created the term and definition does not have its own DPID, a namespace prefix is necessary to make it clear that the namespace is a namespace other than the normal default namespace of a DPID. The namespace prefix needs to be understandable to both sender and recipient.
As shown above, namespace prefix and namespace must be separated by a single colon (":").