with sections regularly updated, printed and distributed, the bsps were the key to the standardized service quality throughout the bell system. they enabled employees, who had never met previously, to easily work with one another in the event of a service outage, a disaster, or merely when relocating. updates cover manufacturing changes phased into production during a product's lifetime of interest to the installer, including changed product features, internal component parts, available colors and installation procedures. collectors also use these documents to help date and restore vintage telephones.