What's this symbol?

[lodilefty]

No, for RUS it would be :
:cbtMaxEntrenchLevel = 4
:cbtMaxEntrenchNotArt = 4

But in some specific towns fortified when an option is activated, you will get there a stack with an entrenched level of 8.

Gamelogic.opt from RUS patch 1.03a:

cbtMaxEntrenchLevel = 8 // Max absolute entrenching level
cbtMaxEntrenchNotArt = 4 // Max entrenching level, if the stack has no artillery (high levels don't benefits non artillery anyway)

[Narwhal]

Well thank you everyone.

I will try to compare with in-game experience

[andatiep]

Well thank you everyone.

I will try to compare with in-game experience

Yes, i can't oppose to Lodilefty any rational code's arguements but i can say that in-game experience don't let you have 8 level entrenchments in RUS (except in few situation as said previously).