This paper presents a design for an experimentum crucis as to the particular type of locality found with the binding of variables ranging over so-called concept generators in the compositional semantics of de re readings of attitude reports (Percus, Sauerland 2003). The outcome of the experiment would show whether Santorio’s (2014) formulation of the locality constraint is adequate. If it is not, this will affect his technical proposal. This paper presents an alternative proposal couched in terms of agreement and thus capable of capturing a more flexible, relative kind of locality.