 that is, everything that is neither obligatory nor prohibited is a matter of indifference. But many actions are neither obligatory nor prohibited, yet they are hardly matters of indifference. A particularly intriguing class of such actions are those that are deemed supererogatory (e.g., volunteering for a costly or risky good endeavor where others are equally qualified and no one person is obligated). SDL can represent optionality, but not indifference, despite the fact that the latter concept has been a purported target for representation since nearly its beginning.