The Core section of a PC's character sheet is, in some ways, more about the Setting's core than the PC's. It typically includes many aspects that are not going to be directly involved in any roll.
Concept, Background, Look, Pronouns and so forth might all be applicable.
In some Settings, notes regarding Gizmos, Magic, Powers and so forth might be in the Core, but the “activating” Attribute will likely be an Energy, as will be discussed below.