You're looking for a text related to the IEC 60439-1 standard. Here is some information:
Type-Tested Assemblies (TTA): These are assemblies that strictly conform to an established design that has passed all required type tests, such as temperature rise limits and short-circuit withstand. iec 60439-1 standard pdf
Under the new IEC 61439 standard, every assembly must be "verified." The focus shifted from "type testing" to "design verification," which can be achieved through testing, comparison with a reference design, or assessment/calculation. Why Engineers Still Search for the IEC 60439-1 PDF You're looking for a text related to the
Elias leaned his forehead against the cold steel of the cabinet. To the outside world, IEC 60439-1 was a dry, technical PDF found on a corporate server. To him, it was the invisible skeleton that kept the modern world from burning down. Because they had followed those thousands of tiny rules, a hospital would keep its lights on, a factory would keep its robots moving, and the Iron King would do its job in total, reliable obscurity. Why Engineers Still Search for the IEC 60439-1
No. Customs and notified bodies in the EU, UK, China, Japan, Australia, and the US (for NRTL marks) will reject a product certified to a withdrawn standard.
The PDF contains specific tables (deep features) regarding creepage distances and clearances. In the older 60439-1, these values were prescriptive.