A large international co-operative project, sponsored by the European Commission, was launched in 1980 aimed at developing common standards for quantitative electrocardiography. The jrst and main objective of the project was to reduce the wide variation in wave measurements currently obtained by electrocardiographic computer programs. To this end a reference library was developed and a comprehensive reviewing scheme was devised for the visual determination of the onsets and offsets of P, QRS and T. This task was performed by a board of cardiologists on highly amplijed recordings, in an interactive four round Delphi-type analysis. The reference library, so obtained, has become an internationally recognized yardstick for the evaluation and improvement of ECG measurement programs. It has been used to test the performance of 9 VCG and 10 standard 12-lead programs. The library proved to be a weful instrument in the establishment of recommendations for more precise measurement rules and dejnitions. Records with added noise and multi-lead ECGs were subsequentlyy analysed to meet specafc objectives. The project was expanded in 1984 towards testing and improvement of diagnostic criteria and classification programs.