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The Bell System Practices was a compilation of technical publications which described the best methods of engineering, constructing, installing, and maintaining the telephone plant of the Bell System under direction of AT&T and Bell Telephone Laboratories.〔A.B. Covey, ''The Bell System's Best Sellers'', Bell Telephone Magazine, Summer 1952 (AT&T)〕 The Bell System Practices cover everything from accounting and human resources procedures through complete technical descriptions of every product serviced by the Bell System, with details specific to the best way to wrap a wire around a screw. With sections regularly updated, printed and distributed, the BSPs were the key to the standardized service quality throughout the Bell System, and enabled employees, who had never met previously, to easily work with one another in the event of a service outage disaster or merely when relocating. Updates covered 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 use these documents to help date and restore vintage phones. ==Document organization== Issuance of Bell System Practices within the Bell System started in the early 1930s, when they replaced a similar compendium, the ''AT&T Specifications''. Initially BSPs were identified by mixed alphanumeric sequence numbers designating a section and a specific document number within each section. The sections consisted of one letter and two digits, followed by a period character and a three-digit document number. The version of each document was indicated by an issue number. For example, the designation ''C34.175 Issue 1'' identified a document entitled ''Station Dials - 2 and 4 Types - Maintenance''. In the 1950s, the format of Practices designations was changed to a nine-digit numerical format, written in three groups of three digits. The first three digits referred to the ''division'', which indicated a broad subject area, such as subscriber sets or the No. 1 ESS. The next three digits indicated a specific subject area, such as specific type of equipment used within the major division subject. The final three digits indicate the serial number of the document. The content could be general descriptive information, information on wiring and connections, test procedures, or piece-part replacement and repair information. The BSP documents were produced in primarily two formats, 8 1/2"x11" pages for use in office environments, and another in a small, 4"x7" portable format for use by installers at customer sites, carried in their service trucks. Starting in the 1970s the most frequently used BSPs were bundled in convenient handbooks each covering general subject matters, such as the ''Station Service Manual''. The format and numbering system was also used by Nortel and ITT Corporation due to their provenance from the Bell System's manufacturing unit, Western Electric. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Bell System Practices」の詳細全文を読む スポンサード リンク
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