Sorry for my English. I write with the help of a translator from google. Please help determine what standards of a graphic symbol electric (number of the standard paragraph, the part number)? In one book in Russia were given 4 image transformer (for drawing in the U.S. and Europe). Аnd did not specify what kind of where taken. Simply written: IEC (DIN) and IEEE (ANSI) After learning standards, I thought: (a) and (b) - IEC 60617 (c) - IEEE 315 Question: Which standards use (d) picture? In general, I met this image more than once Here is an example I only found today site http://www.abacom-online.de/uk/html/splan.html program SPLAN 7 demo screenshot of the program as we see again used this image in general it is a matter of principle to figure out how this symbol electric :) I was told that in 1980 ~ such drawing employed in Germany and now in China. Admittedly this was associated with the use of ASCII artwork "graphics" Well, when CAD has evolved and it symbol "crossed over" into a modern look (ASCII artwork "graphics" --> vector graphics) Help me find a figure emerged from the character and what the normative document is written?