See Programming Perl 4th Edition page 389 - Symbol Tables.

"Symbol tables are stored in a hash whose name is the same as the package, but with two colons appended. The main symbol table's name is thus %main::."

"Likewise, the symbol table or the Red::Blue package is named %Red::Blue::."

James

Also see page 423 - Package-Quoted Classes.

"The final syntactic ambiguity with the indirect object style of method invocation is that it may not be parsed as a method call at all, because the current package may have a subroutine of the same name as the method...there is a way to resolve this ambiguity while still keeping the indirect object syntax: package-quote the class name by appending a double colon to it."

   $obj = method CLASS::;   # forced to be "CLASS"->method