How to recognize core units ??

[tmoj2000]

So I am playing mostly in MP... Quite often units get killed, but it is not possible to rebuild anything because the number of available core units = 0

For example I am playing Germany east, have lost over 20 units, but am still unable to build anything.....

Anyway how do you figure core from non core units ?

[VPaulus]

Core units have a golden border in the strength plate while aux have a silver one.

Take a look at the Common questions sticky: viewtopic.php?t=27283
It might have some useful topics for you to read.

[kjeld111]

The color of the little box surrounding the strength number of the unit, is different, gold vs silver.

[_Flin_]

Do not mix up with the gold border around the flags, though.

I had to reload a two turns of a scenario after I send some infantry and arti to capture a city held by a core unit. And was wondering: what is so strategic about the middle of nowhere?