Why these two variables `${ “_<$filename” }` and `${ “::_<$filename” }` not equal?

Question

This question is related to this one.

You say that these two are same:

${ \"::_<$filename\" }                       # Not allowed under strict.
${ \"_         


        

Answer 1

Thanks to @HåkonHægland. I missed that :: mean main package.

I was messed up by:

the following are equivalent:

${ "::_<$filename" }                       # Not allowed under strict.
${ "_<$filename" }     # In main package   # Not allowed under strict.

Now I understand that means

${ "::_<$filename" }   # This refers to a var in main package
${ "_<$filename" }     # This refers to a var in CURRENT! package