Some types of terminals include ring, tongue, spade, flag, hook, blade, quick-connect, offset and flagged. Once a cable harness has been produced, it is often subject to various tests to ensure its quality and functionality. A test board can be used to measure the harness' electrical capabilities. This is achieved through the input of data about a circuit which one or more cable harnesses will be part of being programmed into the test board. The harness is then measured for its ability to function in the simulated circuit. Another popular test method for a cable harness is a 'pull test', in which the harness is attached to a machine that pulls the harness at a constant rate. This test then measures the cable harness' strength and electrical conductivity when pulled against a minimum standard to ensure that cable harnesses are consistently effective and safe. The cable harnesses used in sound reinforcement and recording studios are called "multicores", also known as "snakes" or "looms". They carry audio signals between a mixing console and stage box. Modern digital mixing consoles typically use a single twisted pair cable rather than a traditional analog multicore. Although customer specifications take the highest priority when creating cable harnesses of a certain quality, in North America if no such specifications are found the quality standards of a cable harness are standardized by the IPC's publication IPC/WHMA-A-620 for minimal requirements for cable harnesses. This publication is reviewed frequently to ensure that the standards published remain of an acceptable standard in light of potential changes to the industry or technology that may occur. The IPC/WHMA-A-620 publication has standards for a wide range of elements within a cable harness, including but not limited to electrostatic discharge protection, conduit, installation and repairs, crimping, pull-test requirements, and other operations that are critical to the production and function of cable harnesses. The standards mandated by the IPC differ based on a product's classification under one of three defined product classes. These classes are: