The ClinicalDocument/id element is an instance identifier data type. The root attribute is an OID. If there is a value in @extension, then the root uniquely identifies the scope of the extension. If there is no value in @extension then @root SHALL uniquely identify the document UUIDs SHALL be represented in the form XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX, where each X is a character from the set [A-Fa-f0-9]. OIDs SHALL be represented in dotted decimal notation, where each decimal number is either 0, or starts with a nonzero digit. More formally, an OID SHALL be in the form ([0-2])(.([1-9][0-9]*|0))+. |