[...]
The notional filename for the named module is generated and returned.
This filename is always in Unix style, with C</> directory separators
and a C<.pm> suffix.  This kind of filename can be used as an argument to
C<require>, and is the key that appears in C<%INC> to identify a module,
regardless of actual local filename syntax.

=cut

sub module_notional_filename($) {
        &check_module_name;
        my($name) = @_;
        $name =~ s!::!/!g;
        return $name.".pm";
}
[...]