Thanks Mike for the link

I've read the whole thread and I can see that I'm not alone to struggle with basic questions...

I do like the answer David Frankenbach made you:

>Undeclared variables are private. Which "functionally makes the public" to any called program.

Even if it is not true if the variable already exists in a calling method, it summarize well enough the behaviour of an undeclared variable according to the called methods...