What does U/C mean on the map of rail gauges of Africa?

Wikipedia has a map of rail gauges of Africa:

It has been used here and there, sometimes to show just how unconnected the rail network is in general with difference of gauges being a problem on top

As you can see in the map legend, there are 2 1435mm types of rail - one with "U/C" mark on it, one without. In some places like Ethiopia one connects to the other, but in f.e. Tanzania or Liberia U/C version is on its own

What does U/C mean?

U/C is a common abbreviation for under construction, meaning the line is not operational yet.

The map's definition of "under construction" seems quite generous though, back in reality eg the shown Rwanda-Tanzania link remains very much on the drawing board.

Likewise, many of the "operational" railways are in reality limited to freight only or are completely out of use.