Civil 3d Text Component editor label expression codes

[KODA]

I have a csv that import and it would be best not to edit it, the point number has value of or similar to 10310106, an 8 digit number.
In the case, I want to remove the last two digits, 06, and end up labeling it 103101, a 6 digit number.
<[Point Number(GC|UN)]>

I found an attachment online but I don't understand what GC or UN or PC means.
any and all help is appreciated.
thank you