II Roots Used by COPPA Services

The [ISO 21090|ISO21090:ISO 21090 Published Standard] II (instance identifier) type is used for all identifiers in the COPPA services.  The two most-used fields in II are root ("a unique identifier that guarantees the global uniqueness of the instance identifier") and extension ("a character string as a unique identifier within the scope of the identifier root").  According to the spec, "The root and extension scheme means that the concatenation of root and extension SHALL be a globally unique identifier for the item that this II value identifies."  A root is typically (but not always) an HL7 OID, although in some cases, it is a string identifier.  Whenever an extension is defined in an II, the root should also be defined, even if the context of the II seems to be enough to identify the extension.  For example, when searching for a trial based on the NCI assigned identifier, the field name "assigned identifier" implies the root, but "2.16.840.1.113883.3.26.4.3" should still be specified for the root explicitly.

The identifier name attribute of the II is "a human-readable name for the namespace represented in the root."  The identifier name does not refer to the organization that issued the identifier but "is intended for use as a human readable label when an identifier must be displayed to a human user where an OID would not be meaningful" - it has no computational value.

Roots Defined by CTRP/COPPA