Hello Minakawa, I'm interesting on the same idea. Because this help us to using the Core Components in a very broad environment and help and will setting up the Core Components as the only one basic structure for building business documents and objects. I have the following answer for your issues: inclusion of common attributes The common attributes are not decided yet within UBL NDRSC. This was only a first draft. The idea of common attributes was that you can define the UBL IDs and the language of tag-names for each element, which will be expressed in every instance. But this is not really resolved yet. We have to discuss about it until January 13th. inclusion of id references (e.g. id= 000107 ) This id expresses the unique Ids of every CC. Not every CC does have an id yet. But if you have any defined yet, you can express this by using the XML-Schema predefined attribute id . inclusion of default values What do you mean with default values? inclusion of CCTs that are not in th e specification (e.g. PercentType, ElectronicAddressType) This is still under discusssion on UBL side. Because we have seen that the xml-schema structures will be much more clear and understandable, if we using a basic xml-schema construction for every secondary represenation term which can be expressed by a specific XML-schema built-in data-type. This makes the schema structure . It does not existing any CC for expressing the URI as an content component. Therefore we defined the additional CCT ElectronicAddressType . You can use this for the representation of standardized and processable EMail addresses as well as for HTML-pages which will be used for further information. naming convention for Identifier (Id or ID) UBL defined ID. Kind regards, Gunther