my @list = grep defined($_), split /
                            \s+
                            |(?<=[A-Z])(?=[0-9]) # letter-number
                            |(?<=[0-9])(?=[A-Z]) # number-letter
                            |
                            (
                                ,
                                |\+
                                |-
                                |\/
                                |&
                            )
                    /xi,
                $string;