In J, what does the suffix "__" do?

Question

I maintain a large code base in J, and a few rare functions and variables end in __(two underscores).

Commonly __used to refer to something in a locale.

barObj =: conew 'Bar'
Foo__barObj

However, I have this:

Foo__

Declared as:

Foo__=: 3 : 0

Is this a different syntax for a static function? Is it available for all locales?

EDIT:

From what I can assemble, it is not local. A variable declared this way:

FooVar__ =.

can refer to another function, despite the fact that it =.makes it local. Similarly, any "locale" declarations are always "global for the locale" ( Foo__Bar =.and Foo__Bar =:match).

Answer 1

- . Locale:

_ , .

abc__ abc_base_

__ _base_ _base_.