All messages developed within DDEX are based upon a common set of elements and their definitions. These are contained in the DDEX Data Dictionary. The full namespace for the XML Schema document for this Standard is:
The full namespace for the XML Schema document for the allowed-value sets is:
DDEX may regularly extend or amend this list of allowed-value sets. Any such extensions to this list that are issued on a date later than the date on which this Standard is issued, form part of this Standard. Thus the list of allowed-value sets provided in Annex A contains the list of allowed-value sets valid on the data of issuance of this Standard.
W3C’s XML Schema Standard has been used to define the structure of the messages and some of the business rules. However, XML Schema alone cannot easily provide a means for complex and conditional validation but XML tools, such as eXtensible Stylesheet Language Transformation (XSLT) and XPath could provide a means of developing standard validation modules for each message set.