This basically allows operations like find references or show hierarchy to focus the results on either all the java sources or from sources excluding test cases. The idea here would be to take this ...

Abstract: It is generally accepted that variables with a narrow syntactic scope can have short names, whereas variables with a broad scope require more informative longer names. We study how names are ...

i.e. intuitively it looks like the variable will only be available within the block but it is accessible outside the block .. in javascript's case, because var doesn't make a block level declaration.