Wire mills around the world each manufacture wire with a variety of requirements and certifications governing their quality. In North America, you will most often see the markings of CSA and/or UL as well as markings specific to industries like automotive and aerospace such as SAE, CE, MIL-XXX etc. depending on application.
Every performance characteristic about a wire is defined within the certifications like maximum operating voltage, flame retardance and burn characteristics, temperature tolerances, insulation thicknesses, platings on conductors.