From a time standard for medical informatics to a controlled language for health.

CEN ENV 12381 is a European Prestandard focusing on formal representation and explicit reference of temporal information in healthcare informatics and telematics. One of its merits is not just the possibility to represent natural language expressions containing time-related information in a structured way, but also to give some mechanisms on how clinical language itself can be used to convey meaning unambiguously. As such, CEN ENV 12381 introduces the notion of 'controlled language use' in the domain of healthcare. In this paper the principles behind controlled language design and use are explained. Through a detailed study of the inconsistencies and ambiguities that arise when interpreting Snomed procedure terms in the framework of the Galen-In-Use project, it is shown that most of them can be explained as a violation of sound term-formation principles. A proposal is made to develop a controlled language for health and to use it in subsequent versions of coding and classification systems. It is expected that such an endeavour will lead to a more effective application of linguistic engineering in areas such as automatic knowledge acquisition, automatic translation, and terminology validation in the domain of healthcare informatics.