Participation is voluntary, subject to agreement to circulate cases as outlined below.
An order of circulation has been drawn up. At the start of each circulation every pathologist in the group is informed of the names and addresses of everyone else in the group, and the latest date by which each pathologist should have dispatched the slides to the next. Participants are invited to comment on the quality of the material circulated, so that feedback on technical matters can be provided to the laboratories which provided the cases. Delay in passing on the slides is the most likely cause for breakdown of the system. A computer generated letter is sent to each pathologist on the date when the slides should have been received, indicating from whom they should have come and asking the pathologist to contact that person if they have not arrived.