Cable U/Uo

[nightfox1925]

In the IEC world, I found cables rated 0.6/1000V, 3.6/6kV etc where it is defined as Uo/U. What is the significance of Uo? Does this description denotes the percent insulation of the cable? I do not find any write up that would give me a clear understanding of this and its associated application.

GO PLACIDLY, AMIDST THE NOISE AND HASTE-Desiderata

 

[davidbeach]

Probably voltage rating to ground (earth) through one cables worth of insulation and voltage rating conductor to conductor through two cables worth of insulation.