[broadgage]

I presume that that the reference was to single core flexible cable with a cross sectional area of ten square millimetres.
The "tri rated" bit means that it conforms to the national standards for 3 different countries, Canada, the USA and the UK. (and is indirectly accepted for use in many other nations that accept one of those three standards)

Primarily intended to simplify the production of equipment for export, but has become the de facto choice for many applications that need a good quality single core flexible.

Pretty the same thing as panel wire, apart from the international approvals, and available in larger sizes, up to at least 50mm.