The words subroutine and function are often used interchangably in perl. (Even perlsub does it!) What I meant by calling shift "not really a function" was that it is very unlike the functions you define in your code, which have a symbol table entry and thus are associated with a package, can have coderefs be taken of them, and be aliased to other names at the symbol table entry, or imported into other packages, in addition to being callable by the & syntax.