Property root : WideString; (Read/Write)
A unique identifier that guarantees the global uniqueness of the instance identifier.
If root is populated, and there is no nullFlavor or extension, then the root is a globally unique identifier in it's own right. In the presence of a non-null extension, the root is the unique identifier for the "namespace" of the identifier in the extension. Note that this does NOT necessarily correlate with the organization that manages the issuing of the identifiers. A given organization may manage multiple identifier namespaces, and control over a given namespace may transfer from organization to organization over time while the root remains the same.
This field can be either a DCE UUID, an Object Identifier (OID), or a special identifier taken from lists that may be published by ISO or HL7.
Comparison of root values is always case sensitive. UUID's SHALL be represented in upper case, so UUID case should always be preserved.
The root SHALL not be used to carry semantic meaning - all it does is ensure global computational uniqueness