Full Idea
The property of being a deepest explanatory feature is a nonmodal property: it's an actual property.
Gist of Idea
Being a deepest explanatory feature is an actual, not a modal property
Source
Alan Sidelle (Necessity, Essence and Individuation [1989], Ch.4)
Book Reference
Sidelle,Alan: 'Necessity, Essence and Individuation' [Cornell 1989], p.126
A Reaction
I don't accept the existence of properties of the form 'being-F'. The possibility of securing a door may be the deepest explanatory feature of a lock. [To be fair to Sidelle, see context - just for once!] Dispositions are actual.