Friday, November 16, 2007

The Dialects of RIM

The latest Minutes of Evidence of the House of Commons Select Committee on Health, on the UK National Programme for IT, contain this comment from Richard Granger:

In terms of the core Spine infrastructure, there was some mythology in the Health Informatics Community that the standards existed, HL7 was mature, and so forth. That was completely untrue.

Dr Granger goes on:
We have had to put an awful lot of effort into specifying the standards for messages, around demographics, around booking, around prescriptions, and then the software that BT have built with a number of sub-contractors is brand new software that has been custom-built for the NHS; so that is high-risk, new build software. There was no other way of doing it. I am very pleased a number of other jurisdictions are getting very interested in using that.
He thereby inadvertently touches on another issue currently causing concern in HL7 circles. The HL7 Reference Information Model or 'RIM' was, we will remember, introduced as the solution to the problems created by the appearance of multiple dialects in earlier versions of the HL7 standard. HL7 would prevent the appearance of dialect versions by enforcing conformity to the RIM. Now, however, it is becoming increasingly clear that the RIM itself exists in multiple dialects.

This is more than just a problem of successive, incremental improvements. As the RIM Document Editorial Assessment from 8 June 2007 points out:
... the 2006 Normative Edition contains a RIM document based on the last balloted RIM [from 2003]: this gap creates the opportunity for conceptual conflict between the document and current practice. A reader must choose between a normative edition of the RIM published for ANSI, which contains nothing extraneous but is out of date; an extract of the current RIM as maintained by MnM, which will be the most up-to-date, but which is not readily available to the membership at large; or, which is most probable, the RIM document published in the Normative Edition, which both contains extraneous information and is out of date.
It seems, in fact, that we have at least:

1. the version of the RIM adopted by ISO as an international standard

2. the balloted RIM document that describes those parts of the RIM designated as 'normative', the latest (and still current) version of which, it seems, dates back to June 2003

3. an ANSI publication based on 2.

4. a CEN Standard EN 14822-1:2005 Health informatics - General purpose information components - Part 1: Overview (see also CEN Standard EN 14720-1:2005), based on 3.

5. the 'living' RIM UML model (regularly updated through harmonization) as it exists at any given stage. This RIM contains content that existed at the time of balloting in 2003 but was not then balloted, together with four years worth of cumulated changes. Some of this material is, I am told, intended to be balloted in the future; some (e.g. in CoreInfrastructure subject area) is not.

6. an idealized 'frozen' version consisting of those parts of 5. which have, at any given stage, passed through the process of harmonization,

7. the UK rebuild.

As I understand matters (and as always this understanding may be for various reasons imperfect) the RIM documentation included in any publication of the V3 standard more recent than 2003 should be based on the latest working version of the model as maintained by the Modeling and Methodology (MnM) committee. The publication label “Normative Edition” may cause confusion, however, if it is taken by the reader as suggesting that the contents so labeled are all normative (though this issue should be addressed in the relevant document preface).