Scope note: This property documents that an E89 Propositional Object has as subject an instance of E1 CRM Entity. This differs from P67 refers to (is referred to by), which refers to an E1 CRM Entity, in that it describes the primary subject or subjects of an E89 Propositional Object. Examples: - the text entitled 'Reach for the sky' (E33) is about Douglas Bader (E21)