Isolationist modifier in BNat file

[marauder]

While taking a look around the Bnat file in the Data folder of the game a few minutes ago, I saw a tag that I either missed completely the last few times or that has just recently been added in an update.
The tag in question is "Isolationist=0" listed for both Italy and Great Britain and set to 0 for both nations.
Now my question is, does anyone know if the tag does anything or when it was added? Or maybe a leftover bit of code from a pre-release version of RtW or SaI?

[director]

Just looked through the manual on making custom nations and I don't see anything about an Isolationist variable. It has been said that a lot of the variables were not used in RtW. You could try changing it for a different nation and see if anything happens.

[Deleted]

not used? Less likely to form alliance/sign treaties? easier to be blockaded??

Ps "eastern" government type: hard to suffer a collapse.