Most livery companies still maintain contacts with their original trade, craft or professional roles. Some still exercise powers of regulation, inspection and enforcement, while others are awarding bodies for professional qualifications. The Scriveners' Company admits senior members of legal and associated professions, the Apothecaries' Society awards post-graduate qualifications in some medical specialties, and the Hackney Carriage Drivers' Company comprises licensed taxi drivers who have passed the "Knowledge of London" test. Several companies restrict membership to those holding relevant professional qualifications, "e.g." the City of London Solicitors' Company and the Worshipful Company of Engineers. Other companies, whose trade died out long ago, such as the Longbow Makers' Company, have evolved into being primarily charitable foundations.