As an example of my confusion about requirements (as I and others have already noted):

• The OPed example strings 'bad" "bad can only be defined (in Perl) by some statement | expression like q{'bad"} q{"bad} respectively. This implies that the double-quotes at the start and end of "hello" and various other examples of valid strings are required parts of the string, and could be defined as q{"hello"} or similar. Is this true?
• What is the classification of '' (or q{}, the empty string)? How about things like q{""} and q{"''"}? Edge cases are important.