Use of UUIDs in II.extension
This page documents a Resolved, but not fully actioned MnM Hot Topic, i.e. a methodology issue requiring a resolution from Modeling and Methodology.
This page documents an INM Workitem, i.e. an issue within scope of the INM Committee that either is still being discussed, or the resolution of which has not yet been included in an INM ballot.
Issues
There are two views about whether it is appropriate to send a UUID (GUID) in the II.extension property:
1. It's perfectly ok. The II.root represents the assigning authority which provides semantic context for the UUID issued.
2. It's not terribly appropriate and meaningless. The II.root is not intended to convey semantics, merely ensure uniqueness. UUIDs are already globally unique, so having a separate root is just extra overhead. All semantics are conveyed by other RIM attributes (e.g. Role.classCode, Role.code, Role.scoper, Act.classCode, Act.code, Act.moodCode
So: which is it? (see the discussion page for details)
Resolution
20070108 MnM/INM: Motion to add "The normal mechanism for transmitting a UUID (DCE Universal Unique Identifier) as an identifier is to send it as the root with no extension. A UUID expressed as an extension is not considered to be a match for a UUID in the root. I.e. A match is required on both root and extension to be considered a match. The root can be used to identify a namespace. The design of HL7 specifications SHALL never assume that receiving applications can infer the identity of the scoper or issuer, or the type of the identifier from the namespace identifier." to datatypes R2. (Grahame/ Lee, x-0-1)
