The drone program needs to come out of the shadows, with explanations about who is a civilian, who is a target, and how drone operators distinguish between the two.

CNN: Bring drones out of the shadows

It also is an effort to distinguish between those who report business income on their individual returns and actual small businesses.

FORBES: Small Biz Not The Job Creator It's Been Cracked Up To Be

Dr Pey, who is registered blind and can only distinguish between light and dark, described the experience on 2 February as "distressing".

BBC: Blind Eurostar passenger left stranded in Brussels

It is, for example, easy to distinguish between a project engineer, who downloads drawings to build the required parts, and a project administrator, who views those drawings more sporadically in order to chart progress, but does not actually download them on to his own computer.

ECONOMIST: Network collaborations: The big picture | The