York Ac Schematics Y14 - DOE-HDBK-1016/1-93 ENGINEERING SYMBOLOGY, PRINTS, AND DRAWINGS. ABSTRACT The Engineering Sym bology, Prints, and Drawings Handbook was developed to assist nuclear facility operating contractors in providing operators, maintenance personnel, and technical staff with the necessary fundamentals training to ensure a basic understanding of engineering prints, their use, and. A phone connector, also known as phone jack, audio jack, headphone jack or jack plug, is a family of electrical connectors typically used for analog audio signals. The phone connector was invented for use in telephone switchboards in the 19th century and is still widely used. The phone connector is cylindrical in shape, with a grooved tip to retain it.