When registration opens, some workshops will be fully subscribed very quickly. Some authors may want to contact participants before the workshop day (e.g. to assign preparatory tasks, to send hardware or materials to participants, or to organise a 'call' for presentations). At NIME 2020, we decided that it was more effective if workshop authors liaised directly with participants (rather than communicating via the workshop chairs). In consultation with the conference organisers, we decided that only people who were registered for the conference could attend workshops.