Yes - you have understood the sequence correctly.
in reply to Re^2: Canon concerning coderef calls?
in thread Canon concerning coderef calls?
The relevant document is the "Symbol Table" section of perlmod.
The symbol table for a package happens to be stored in the hash of that name with two colons appended. The main symbol table's name is thus %main::, or %:: for short. ...
Hence "$::" is de-referencing the "%main::" hash, using "$_" as the key. The following parens prvide the "sub" context, and allow the sub to be passed the $_ param.
Earth first! (We'll rob the other planets later)