Friday, April 29, 2011

ISO TR 12310 Draft Standard - Problems and Issues

A draft of the ISO TR 12310 standard came across our desks in the last day or two, and we were surprised at the substantial problems that exist in its fundamental components. The title of the standard is "Health informatics — Principles and guidelines for the measurement of conformance in the implementation of terminological systems".

First, it defines a concept as "A concept is a single mental representation of some real or abstract thing."

This definition is problematic, because never in the history of terminological systems has anyone elucidated a theory of a basic unit of mental representation. What is a single mental representation? Or a unit of thought (as concept has also been defined)?

If I'm thinking of a car, is that a unit of thought? What if I'm thinking about a particular red, C-class Mercedes Benz with a particular Vehicle Identification Number? Or what if I'm just thinking about red, C-class Mercedes owned by stock brokers and that need new brakes and on which a tree fell during a Spring storm, in general? How many unique mental representations are there? One, two, three? How do we count unique ideas and single mental representations?

This question is not trivial, as the answer determines what concept representations we are permitted to have. Historically, the answer has been that anything anyone wants to put in the system is allowable. For a real-world example, consider the following "concept" from SNOMED CT: Family history of myocardial infarct in first degree female relative less than 65 years of age (situation).

The draft standard then goes on to say: "Concepts are should be unique within a code system." The grammatical problem aside, the standard is now engaged in use-mention confusion. For your mental representations are not part of any code system! The standard is using the word concept for both representations of concepts and concepts (themselves mental representations).

The draft standard then goes on to say: "A concept representation is a mechanism by which the system can express a concept." So it should be concept representations that are unique within a code system, not concepts.

But then the standard says: "Most code systems support multiple representations for each concept, sometimes even multiple representations of a given type."

How do code systems support interoperability, then?

Next, we are told that a "Concept id" is "A concept representation that is unique within the code system and that is used internally by the code system when referencing concepts."

Does that mean we cannot use concept ids outside the code system, either because it's impossible or disallowed? Surely some software applications are using SNOMED CT concept ids external to SNOMED CT itself? Are they out of conformance?

And that covers just pages 1 and 2.