Kim returned to her desk after a long and difficult meeting. On her desk was a message that said: ‘Chris rang. Please ring back within the next hour.’ There were three problems with this message. First, she knew two Christines, three Christophers and one Christian – all known as Chris. Which one had actually rung? Second, there was no time on the message, and so she did not know when ‘within the next hour’ referred to, as she had been away from her desk for nearly three hours. Third, there was no name on the note and she did not recognize the handwriting. It was therefore going to be difficult and time-consuming to trace who had left the note in order to clarify the message.