Working Group 1 (WG1) of the Joint Committee for Guides in Metrology (JCGM) has responsibility for maintaining the Guide to the Expression of Uncertainty in Measurement (GUM). The principles of the GUM are now used worldwide at all levels of the measurement chain, i.e. from NMIs to industry. In consequence, it would probably be counterproductive to produce a new version of the GUM at this time although the Group is aware that it could be improved. The JCGM-WG1 has thus decided to produce Supplements to the GUM to cover some topics of interest in more detail, whilst also directing them to groups of users with different levels of expertise. In addition, the Group is preparing an introductory document to promote the sound evaluation of measurement uncertainty through the use of the GUM. In these new documents, the concepts and notations are kept coherent with the GUM, with the maximum possible reference being made to the principles and concepts of the GUM.

	Chairman:	Dr W. Bich [ISO] Istituto Nazionale di Ricerca Metrologica (INRIM) Strada delle Cacce, 73 I-10135 TURIN Italy
	BIPM contact:	Dr C. Michotte Bureau International des Poids et Mesures Pavillon de Breteuil 92312 SÈVRES CEDEX France	Contact form:

Members of the JCGM-WG1 (GUM)
	Prof. Maurice Cox [BIPM]	National Physical Laboratory (NPL), Centre for Mathematics and Scientific Computing, Teddington
	Dr René Dybkær [IFCC]	H:S Copenhagen Hospital Corporation-Frederiksberg Hospital, Department of Standardization in Laboratory Medicine, Frederiksberg
	Dr Charles D. Ehrlich [ISO and OIML]	National Institute of Standards and Technology (NIST), Weights and Measures Division, Gaithersburg
	Dr W. Tyler Estler [BIPM]	National Institute of Standards and Technology (NIST), Precision Engineering Division, Gaithersburg
	Prof. Brynn Hibbert [IUPAC]	School of Chemistry, University of New South Wales, Sydney
	Dr Hidetaka Imai [ILAC]	National Institute of Technology and Evaluation (NITE), Tokyo
	Mr Willem Kool [OIML]	Bureau International de Métrologie Légale, Paris
	Dr Lars Nielsen [BIPM]	Danish Institute of Fundamental Metrology (DFM), Lyngby
	Dr Leslie Pendrill [IUPAP]	Measurement Technology, Swedish National Testing and Research Institute (SP), Borås
	Prof. Lorenzo Peretto [IEC]	Department of Electrical Engineering, University of Bologna, Bologna
	Dr Antonio Possolo [ISO]	National Institute of Standards and Technology (NIST), Statistical Engineering Division, Gaithersburg
	Prof. Graham H. White [IFCC]	Dept. of Medical Biochemistry, Flinders Medical Centre, Bedford Park
	Dr Wolfgang Wöger [IUPAP]	Drosselweg 1, D-50735 Cologne