Response-specific feedback in List questions

[afullo]

Hi all,

I see here that, also in List questions and not only in Multiple Choice questions, for each specified incorrect answer, it can be defined response-specific feedback. But I'm unable to find the option by editing, and manually adding in the source code rows of the kind comment.<n>=<comment_text>@, as proposed here for the MC case, does not work. How can I perform such an addition?

Thanks in advance.