25+ year old 14/3 extension cord. Blue jacket. Still nice and flexible. Jacket stamped "-50C". Surprisingly, it is also stamped "SJTW-A". I thought flexible-in-cold carried the E, not the T designation. What is it that makes some extension cords flexible in cold weather?
You may notice a child's outdoor toy blanches and cracks in 6 months from UV from sunlight, but your car's interior holds up for 20 years despite much hotter conditions. It is a different grade of plastic.
Also, nothing requires a cable claim every rating it's entitled to, or it may comply mostly, but fall technically short of what is needed for the rating. You're always allowed to make a great product.
Flexible cords have an entire section of the National Electric Code article 400. If I remember correctly T is thermoplastic, SJ is junior hard service, W is damp/ wet locations. I really don't remember A in a description.