Short for International Electrotechnical Commission, an international standards body. Responsible for standards such as the socket on the back of your PC or on your power adapter where you plug in the mains lead. According to 
Wikipedia, their standards have numbers in the range 60000–79999. In which case, how do you explain
IEC958
another name for S/PDIF, as near as I can tell. This is the optical connector on your sound card or your PC’s onboard sound hardware.
One page links to IEC:
